With the Session Initiation Protocol (SIP), it is possible to have telephony on IP network that is originally intended only for computer communication and not communication between human being. The convergence dream is hence realized but it does not stop there. From the fixed network, the Internet Protocol continues its expansion to the mobile network and the next phase 3G networks will be totally based on IP. It is therefore natural to extend the usage of SIP to mobile networks as well. The 3GPP has specified the IP Multimedia Subsystem (IMS) based on SIP that will make IP telephony on mobile networks. Unfortunately, due to the intrinsic differences between the mobile network and the fixed one, many modifications must be introduced and IMS ends up different to the original SIP. The relevant question is then whether IMS can be used both for mobile and fixed networks.
The goal of this thesis work is to find the answer to this question. All the challenges are identified and studied carefully. The solutions are also proposed.
This thesis starts with an introduction og the Session Initiation Protocol (SIP) and IP Multimedia Subsystem (IMS). Next, it identifies the IMS extensions to the core SIP protocol and analyses the differences between IMS and SIP
Three scenarios for IMS and SIP integration as follows have been analysed carefully:
Interworking between IMS and SIP Roaming between IMS and SIP IMS access through any network and devices
For the scenarios 1, Interworking between IMS and SIP, an B2BUA (Back to back user agent) is needed at the interface between IMS and SIP. For the scenarios 2, Roaming between IMS and SIP, a SIP agent is required on mobile devices in addition to the IMS client. For the scenario 3, IMS access through any network and devices, stationary devices like PC, laptop, tabletPC, etc. must be equipped with UICC to comply with IMS..
The general conclusion is that it is possible to use IMS both for mobile and fixed networks but further works are required in many areas in order to achieve it.: