I was just reading about British Telecom (BT) and their planned rollout of 21CN (The 21st Century Network), where they plan to rip out the heart of their telephone network and replace everything with IMS, the IP Multimedia Subsystem. This is quite a radical move, the first fixed-line operator I have heard of that is going for an IMS core.

So by 2010, the whole network will be 100% SIP, with only VoIP travelling across the core network. Of course some legacy stuff will still have to exist to support customers that have not committed to going IP yet, so BT plan to build what they call “Metro Nodes”, which terminate all the “old” technologies and convert everything to IP. So anything from analogue phone line to E1 to SS7 to broadband will all live in the Metro Node, allowing the core to be dedicated IP.

Franz-Joseph Eberle
Eicon Networks
Diva Server Product Manager