I got a pretty interesting email from BT this week, regarding a site called web21c that they have just opened as a 'sneak peek'. On the site they have documentation and code samples (for Visual Studio 2005), allowing developers to control features in the PSTN network. It's good to see a telco talking the language of "Web 2.0", with published .NET APIs, and an 'early look' site to hook new developers in.

I haven't had time to look through the material in detail to see what's there, but it will be interesting to see what features can be controlled. I can see that call control and SMS are in the list, but as far as I'm aware the promised IMS core network (in the BT 21CN, or "21st Century Network"), is so far only available in one UK city, Cardiff. So it's not clear what you can actually do with the API today.