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A method in a communication system wherein a user (1) is arranged to register with a control entity (22) comprises sending a message from the communication system to the user (1) requesting that the user re-register with said communication network. The user is caused to re-register with said network

A method in a communication system wherein a user (1) is arranged to register with a control entity (22) comprises sending a message from the communication system to the user (1) requesting that the user re-register with said communication network. The user is caused to re-register with said network in response to said message.

대표청구항 ▼

1. A method, comprising: registering a user equipment with a control entity in a communication system, said control entity implemented as a serving call state control function;sending a message from the communication system to the user equipment requesting that the user equipment re-register with sa

1. A method, comprising: registering a user equipment with a control entity in a communication system, said control entity implemented as a serving call state control function;sending a message from the communication system to the user equipment requesting that the user equipment re-register with said communication system, the sending is responsive to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipment; andcausing said user equipment to re-register with said communication system in response to said message wherein said user equipment is re-authenticated when said user equipment is re-registered,wherein re-registration of said user equipment is carried out without dropping existing sessions associated with the user equipment. 2. The method of claim 1, wherein the sending the message is performed by said control entity. 3. The method of claim 1, wherein the sending said message is responsive to an occurrence of one or more specified conditions. 4. The method of claim 1, further comprising: configuring the control entity error conditions to comprise one or more of the following conditions: congestion in said system; andoverloading in said system. 5. The method of claim 1, wherein the sending the user equipment said message is performed conditioned on whether the user equipment subscribes to a service providing said message. 6. The method of claim 1, wherein the sending the message comprises sending the message to the user equipment from the control entity via an intermediate control entity. 7. The method of claim 6, further comprising: configuring said intermediate control entity to be a proxy call state control function. 8. The method of claim 1, further comprising: sending, by said user equipment, a re-registration request in response to said message. 9. A method, comprising: authenticating a user equipment with a control entity in a communication system, said control entity implemented as a serving call state control function;sending a message from the communication system to the user equipment requesting that the user equipment initiate a procedure with said communication system, said procedure causing re-authentication of said user equipment, the sending is responsive to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipment;causing said user equipment to initiate said procedure in response to said message; andre-authenticating said user equipment,wherein said procedure is carried out without dropping existing sessions associated with the user equipment. 10. The method of claim 9, wherein the sending the message is performed by said control entity. 11. The method of claim 9, wherein the sending said message is responsive to an occurrence of one or more specified conditions. 12. The method of claim 9, further comprising: configuring the control entity error conditions to comprise one or more of the following conditions:congestion in said system; andoverloading in said system. 13. The method of claim 9, wherein the sending the user equipment said message is conditioned on whether the user equipment subscribes to a service providing said message. 14. The method of claim 9, wherein the sending the message comprises sending the message to the user equipment from the control entity via an intermediate control entity. 15. The method of claim 14, further comprising: configuring said intermediate control entity to be a proxy call state control function. 16. The method of claim 9, further comprising: configuring said communication system to be a third generation communications network. 17. The method of claim 9, further comprising: configuring said message to be a session initiation protocol NOTIFY message. 18. A system, comprising: a user equipment; anda control entity, said control entity implemented as a serving call state control function,wherein the user equipment is configured to be registered with the control entity,wherein said communication system is configured to send a message to the user equipment requesting that the user equipment re-register with said communication system, the message is sent in response to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipmentwherein said user equipment is configured to re-register with said communication system in response to said message,wherein said user equipment is re-authenticated when said user equipment is re-registered, andwherein said communication system is configured to carry out re-registration of said user equipment without dropping existing sessions associated with the user equipment. 19. The communication system of claim 18, wherein the user equipment comprises a mobile user equipment. 20. The system of claim 18, wherein said control entity is configured to send said message. 21. The system of claim 18, wherein said message is configured to be sent in response to an occurrence of one or more specified conditions. 22. The system of claim 18, wherein the control entity error conditions comprise one or more of the following conditions: congestion in said system; andoverloading in said system. 23. The system of claim 18, wherein the message is configured to be sent to the user equipment conditioned upon whether the user equipment subscribes to a service providing said message. 24. The system of claim 18, wherein the control entity is configured to send the message to the user equipment via an intermediate control entity. 25. The system of claim 24, wherein said intermediate control entity is a proxy call state control function. 26. The system of claim 18, wherein said user equipment is configured to send a re-registration request in response to said message. 27. The system of claim 18, wherein said communication system is a third generation communications network. 28. The system of claim 18, wherein said message is a session initiation protocol NOTIFY message. 29. An apparatus, comprising: a processor configured to register a user equipment with a control entity in a communication system, said control entity implemented as a serving call state control function; anda transmitter configured to send a message to the user equipment requesting that the user equipment re-register with the communication system, the message is sent in response to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipment,wherein the message is configured to trigger the user equipment to re-register with the communication system in response to the message, without requiring said user equipment to drop existing sessions associated with said user equipment. 30. An apparatus, comprising: registration means for registering a user equipment with a control entity in a communication system, said control entity implemented as a serving call state control function; andsender means for sending a message to the user equipment requesting that the user equipment re-register with the communication system, the message is sent in response to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipment,wherein the message is configured to trigger the user equipment to re-register with the communication system in response to the message, without requiring said user equipment to drop existing sessions associated with said user equipment. 31. A method, comprising: receiving a message, at a user equipment in a communication system wherein the user equipment is configured to register with a control entity implemented as a serving call state control function, from the communication system requesting that the user equipment re-register with said communication network, the message is received in response to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipment; andcausing said user equipment to re-register with said network in response to said message wherein said user equipment is re-authenticated when said user equipment is re-registered,wherein re-registration of said user equipment is carried out without dropping existing sessions associated with said user equipment. 32. An apparatus, comprising: a processor of a user equipment configured to operate in a communication system, wherein said user equipment is configured to be registered with a control entity in operation, the control entity implemented as a serving call state control function;a receiver configured to receive a message from the communication network requesting that the user equipment re-register with said communication network, the message is received in response to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipment;wherein said processor is configured to re-register said user equipment with said network in response to said message,wherein said user equipment is re-authenticated when said user equipment is re-registered, andwherein said processor is configured to re-register the user equipment with the network without dropping existing sessions associated with the user equipment. 33. The apparatus of claim 29, wherein the user equipment comprises a mobile user equipment. 34. The apparatus of claim 29, wherein said message is configured to be sent in response to an occurrence of one or more specified conditions. 35. The apparatus of claim 29, wherein the error conditions comprise one or more of the following conditions: congestion in said system; andoverloading in said system. 36. The apparatus of claim 29, wherein the message is configured to be sent to the user equipment conditioned upon whether the user equipment subscribes to a service providing said message. 37. The apparatus of claim 29, wherein the apparatus is configured to send the message to the user equipment via an intermediate control entity. 38. The apparatus of claim 37, wherein said intermediate control entity is a proxy call state control function. 39. The apparatus of claim 29, wherein said user equipment is configured to send a re-registration request in response to said message. 40. The apparatus of claim 29, wherein said communication system is a third generation communications network. 41. The apparatus of claim 29, wherein said message is a session initiation protocol NOTIFY message. 42. The apparatus of claim 32, wherein the user equipment comprises a mobile user equipment. 43. The apparatus of claim 32, wherein said control entity is configured to send said message. 44. The apparatus of claim 32, wherein said message is configured to be sent in response to an occurrence of one or more specified conditions. 45. The apparatus of claim 32, wherein the control entity error conditions comprise one or more of the following conditions: congestion in said system; andoverloading in said system. 46. The apparatus of claim 32, wherein the message is configured to be sent to the user equipment conditioned upon whether the user equipment subscribes to a service providing said message. 47. The apparatus of claim 32, wherein the control entity is configured to send the message to the user equipment via an intermediate control entity. 48. The apparatus of claim 47, wherein said intermediate control entity is a proxy call state control function. 49. The apparatus of claim 32, wherein said user equipment is configured to send a re-registration request in response to said message. 50. The apparatus of claim 32, wherein said communication system is a third generation communications network. 51. The apparatus of claim 32, wherein said message is a session initiation protocol NOTIFY message. 52. A computer-readable medium encoded with instructions that, when executed on a computer, perform a process, the process comprising: registering a user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;sending a message from the communication system to the user equipment requesting that the user equipment re-register with said communication system, the sending is responsive to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipment; andcausing said user equipment to re-register with said communication system in response to said message wherein said user equipment is re-authenticated when said user equipment is re-registered,wherein re-registration of said user equipment is carried out without dropping existing sessions associated with the user equipment. 53. A computer-readable medium encoded with instructions that, when executed on a computer, perform a process, the process comprising: authenticating a user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;sending a message from the communication system to the user equipment requesting that the user equipment initiate a procedure with said communication system, said procedure causing re-authentication of said user equipment, the sending is responsive to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipment;causing said user equipment to initiate said procedure in response to said message; andre-authenticating said user equipment,wherein said procedure is carried out without dropping existing sessions associated with the user equipment. 54. A computer-readable medium encoded with instructions that, when executed on a computer, perform a process, the process comprising: receiving a message, at a user equipment in a communication system wherein the user equipment is configured to register with a control entity implemented as a serving call state control function, from the communication system requesting that the user equipment re-register with said communication network, the message is received in response to at least one of a plurality of specified conditions, the plurality of specified conditions comprising one or more of the following: a current registration of the user equipment is set to expire in a predetermined time;one or more error conditions in the communication system;one or more error conditions in the control entity; andthe communication system mistrusts the user equipment; andcausing said user equipment to re-register with said network in response to said message wherein said user equipment is re-authenticated when said user equipment is re-registered,wherein re-registration of said user equipment is carried out without dropping existing sessions associated with said user equipment. 55. A method, comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least one of a plurality of specified conditions; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 56. The method of claim 55, wherein the message comprises a session initiation protocol NOTIFY message. 57. The method of claim 55, wherein the re-registration further comprises the re-authentication. 58. A method, comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least a current registration of the user equipment set to expire in a predetermined time; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 59. The method of claim 58, wherein the message comprises a session initiation protocol NOTIFY message. 60. The method of claim 58, wherein the re-registration further comprises the re-authentication. 61. A method, comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message responsive to at least one or more error conditions in the communication system; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 62. The method of claim 61, wherein the message comprises a session initiation protocol NOTIFY message. 63. The method of claim 61, wherein the re-registration further comprises the re-authentication. 64. A method, comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least one or more error conditions in the control entity; andcausing, in response to the message, the-user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 65. The method of claim 64, wherein the message comprises a session initiation protocol NOTIFY message. 66. The method of claim 64, wherein the re-registration further comprises the re-authentication. 67. A method, comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least the control entity mistrusting the user equipment; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 68. The method of claim 67, wherein the message comprises a session initiation protocol NOTIFY message. 69. The method of claim 67, wherein the re-registration further comprises the re-authentication. 70. An apparatus, comprising: a transmitter configured to send a registration message to register a user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function; anda receiver configured to receive, at the user equipment, a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least one of a plurality of specified conditions, wherein the transmitter is configured to cause, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered, wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 71. The apparatus of claim 70, wherein the message comprises a session initiation protocol NOTIFY message. 72. The apparatus of claim 70, wherein re-registration comprises re-authentication. 73. An apparatus, comprising: a transmitter configured to send a registration message to register a user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function; anda receiver configured to receive, at the user equipment, a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least a current registration of the user equipment set to expire in a predetermined time, wherein the transmitter is configured to cause, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered, wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 74. The apparatus of claim 73, wherein the message comprises a session initiation protocol NOTIFY message. 75. The apparatus of claim 73, wherein re-registration comprises re-authentication. 76. An apparatus, comprising: a transmitter configured to send a registration message to register a user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function; anda receiver configured to receive, at the user equipment, a message requesting the user equipment to re-register with the communication system, wherein the message responsive to at least one or more error conditions in the communication system, wherein the transmitter is configured to cause, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered, wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 77. The apparatus of claim 76, wherein the message comprises a session initiation protocol NOTIFY message. 78. The apparatus of claim 76, wherein re-registration comprises re-authentication. 79. An apparatus, comprising: a transmitter configured to send a registration message to register a user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function; anda receiver configured to receive, at the user equipment, a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least one or more error conditions in the control entity, wherein the transmitter is configured to cause, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered, wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 80. The apparatus of claim 79, wherein the message comprises a session initiation protocol NOTIFY message. 81. The apparatus of claim 79, wherein re-registration comprises re-authentication. 82. An apparatus, comprising: a transmitter configured to send a registration message to register a user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function; anda receiver configured to receive, at the user equipment, a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least the control entity mistrusting the user equipment, wherein the transmitter is configured to cause, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered, wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 83. The apparatus of claim 82, wherein the message comprises a session initiation protocol NOTIFY message. 84. The apparatus of claim 82, wherein re-registration comprises re-authentication. 85. An apparatus comprising: at least one processor; andat least one memory including code, which when executed by the at least one processor provide operations comprising:sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least one of a plurality of specified conditions; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 86. The apparatus of claim 85, wherein the message comprises a session initiation protocol NOTIFY message. 87. The apparatus of claim 85, wherein re-registration comprises re-authentication. 88. An apparatus comprising: at least one processor; andat least one memory including code, which when executed by the at least one processor provide operations comprising:sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least a current registration of the user equipment set to expire in a predetermined time; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 89. The apparatus of claim 88, wherein the message comprises a session initiation protocol NOTIFY message. 90. The apparatus of claim 88, wherein re-registration comprises re-authentication. 91. An apparatus comprising: at least one processor; andat least one memory including code, which when executed by the at least one processor provide operations comprising:sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message responsive to at least one or more error conditions in the communication system; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 92. The apparatus of claim 91 wherein the message comprises a session initiation protocol NOTIFY message. 93. The apparatus of claim 91, wherein re-registration comprises re-authentication. 94. An apparatus comprising: at least one processor; andat least one memory including code, which when executed by the at least one processor provide operations comprising:sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least one or more error conditions in the control entity; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 95. The apparatus of claim 94, wherein the message comprises a session initiation protocol NOTIFY message. 96. The apparatus of claim 94, wherein re-registration comprises re-authentication. 97. An apparatus comprising: at least one processor; andat least one memory including code, which when executed by the at least one processor provide operations comprising:sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least the control entity mistrusting the user equipment; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 98. The apparatus of claim 97, wherein the message comprises a session initiation protocol NOTIFY message. 99. The apparatus of claim 97, wherein re-registration comprises re-authentication. 100. A computer-readable medium encoded with instructions that, when executed on a computer, perform a process, the process comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least one of a plurality of specified conditions; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 101. The computer-readable medium of claim 100, wherein the message comprises a session initiation protocol NOTIFY message. 102. The computer-readable medium of claim 100, wherein the re-registration further comprises the re-authentication. 103. A computer-readable medium encoded with instructions that, when executed on a computer, perform a process, the process comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least a current registration of the user equipment set to expire in a predetermined time; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 104. The computer-readable medium of claim 103, wherein the message comprises a session initiation protocol NOTIFY message. 105. The computer-readable medium of claim 103, wherein the re-registration further comprises the re-authentication. 106. A computer-readable medium encoded with instructions that, when executed on a computer, perform a process, the process comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message responsive to at least one or more error conditions in the communication system; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 107. The computer-readable medium of claim 106, wherein the message comprises a session initiation protocol NOTIFY message. 108. The computer-readable medium of claim 106, wherein the re-registration further comprises the re-authentication. 109. A computer-readable medium encoded with instructions that, when executed on a computer, perform a process, the process comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least one or more error conditions in the control entity; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 110. The computer-readable medium of claim 109, wherein the message comprises a session initiation protocol NOTIFY message. 111. The computer-readable medium of claim 109, wherein the re-registration further comprises the re-authentication. 112. A computer-readable medium encoded with instructions that, when executed on a computer, perform a process, the process comprising: sending, by a user equipment, a registration message to register the user equipment with a control entity in a communication system, the control entity implemented as a serving call state control function;receiving at the user equipment a message requesting the user equipment to re-register with the communication system, wherein the message is responsive to at least the control entity mistrusting the user equipment; andcausing, in response to the message, the user equipment to re-register with the control entity in the communication system, wherein the user equipment is re-authenticated when the user equipment is re-registered,wherein the re-registration of the user equipment is carried out without dropping existing sessions associated with the user equipment. 113. The computer-readable medium of claim 112, wherein the message comprises a session initiation protocol NOTIFY message. 114. The computer-readable medium of claim 112, wherein the re-registration further comprises the re-authentication.