Swisscom is pursuing one of the easiest roadmaps to IMS. Ericsson has deployed the core IMS components (CSCF) and will be integrating three separate network components of Swisscom.
Three different network components or service offerings that Swisscom will integrate to achieve one of the first widescale IMS compliant networks are: fixed line Voice-over-Broadband, residential mobile service, and a converged component. The converged component consists of a single phone number that services both the mobile phone as well as fixed phone.
The residential mobile offering (not yet in service) will be hosted off the same VoIP application server platform that serves the fixed VoBB customers. Converged offering will serve both mobile and fixed phones off the same feature server i.e. simultaneous ring etc. Native VCC is also being tested in addition but has not been implemented yet. Swisscom is also putting in border entities that allow GSM call/session flow into the IMS.
Only residential VoBB offer is out on offer. The mobile and converged parts are going to be offered by early 2008. By then Swisscom hopes to have a full blown IMS network in place that offers mainstream telephony services to both fixed and mobile users.