System and method for network assisted multi-line registration in an IMS network

A multi-line network registration capability for an IMS network is disclosed. Registration with a Home IMS domain is used for a user equipment (UE) device to authenticate to the IMS network infrastructure. IMS network infrastructure expects each UE to have a single identity (e.g., IMPI/IMPU pair) on the network. A multiple back to back registration (MB2B) module may optionally provide multiple identities to a single UE device. Multiple identities may be associated with a service plan provided for the IMPI/IMPU unique identifier. Infrastructure of the Home IMS domain may be used to support the multiple identities for a given UE device. Accordingly, the MB2B module may not require any additional infrastructure changes by other service providers. The MB2B module may be implemented as a software upgrade to existing infrastructure devices or may be implemented as a standalone front-end device to assist in performing registrations for a telco service provider.