IP multimedia subsystem user identity handling

An apparatus configured to implement a Home Subscriber Server within an IP Multimedia Subsystem (IMS) network, the apparatus comprising:

• a memory;
• and
• a processor coupled to the memory configured to execute programmed instructions stored in the memory which cause the processor to:
• receive from a Call Session Control Function a Cx query pertaining to an IMS registration of an IP Multimedia Public Identity, the Cx query including the IP Multimedia Public Identity and a derived IP Multimedia Private Identity that was derived from the IP Multimedia Public Identity;
• identify a subscription using said IP Multimedia Public Identity, determine that the derived IP Multimedia Private Identity is not associated with said subscription, and identify a default IP Multimedia Private Identity associated with said subscription;
• and
• return a Cx response to said Call Session Control Function including said default IP Multimedia Private Identity.

An apparatus configured to implement a Call Session Control Function within an IP Multimedia Subsystem network, the apparatus comprising:

• a memory;
• and
• a processor coupled to the memory configured to execute programmed instructions stored in the memory which cause the processor to:
• receive a SIP REGISTER message including a completed IP Multimedia Public Identity Attribute-Value-Pair and no IP Multimedia Private Identity;
• derive an IP Multimedia Private Identity using the IP Multimedia Public Identity indicated in the completed IP Multimedia Public Identity Attribute-Value-Pair;
• send a Cx query to a Home Subscriber Server, the query including the IP Multimedia Public Identity and the derived IP Multimedia Private Identity;
• receive from the Home Subscriber Server a Cx response, the response including a default IP Multimedia Private Identity;
• and
• use the received, default IP Multimedia Private Identity to further handle said SIP REGISTER message.

A method implemented by a Home Subscriber Server within an IP Multimedia Subsystem network, comprising:

• receiving from a Call Session Control Function a Cx query pertaining to an IMS registration of an IP Multimedia Public Identity, the query including the IP Multimedia Public Identity and a derived IP Multimedia Private Identity that was derived from the IP Multimedia Public Identity;
• identifying a subscription using said IP Multimedia Public Identity;
• determining that the derived IP Multimedia Private Identity is not associated with said subscription;
• identifying a default IP Multimedia Private Identity associated with said subscription;
• and
• returning a Cx response to said Call Session Control Function including said default IP Multimedia Private Identity.

A method implemented by a Call Session Control Function node within an IP Multimedia Subsystem network, comprising:

• receiving a SIP REGISTER message including a completed IP Multimedia Public Identity Attribute-Value-Pair and no IP Multimedia Private Identity;
• deriving an IP Multimedia Private Identity using the IP Multimedia Public Identity indicated in the completed IP Multimedia Public Identity Attribute-Value-Pair;
• sending a Cx query to a Home Subscriber Server, the query including the IP Multimedia Public Identity and the derived IP Multimedia Private Identity;
• receiving from the Home Subscriber Server a Cx response, the response including a default IP Multimedia Private Identity;
• and using the received, default IP Multimedia Private Identity to further handle said SIP REGISTER message.