Multiaccess architecture to the 3G mobile services

The 3GPP selected the session initiation protocol (SIP) for the IP core network multimedia subsystem (IMS), enabling multimedia session control in 3GPP wireless networks. However, the IMS is restricted to the supported users as defined by 3GPP. We propose in this paper to extend the supported accesses (3GPP and WLAN) to other types of accesses (xDSL, CATV). The possibility to offer evolved SIP services through IMS to non3GPP access based users, leverages the multimedia services provided by operators. Such interworking introduces hence new gateways to the edge interfaces of networks: to allow user access and billing, to determine traffic path or simply transfer the policies between networks. The paper focuses on these required gateways, their role in the architecture and in the SIP messages flow. We also look at the new issues that rise with the interconnection of 3GPP network with different networks.