British Telecom are making changes to the telephone network.   This change will transfer all voice calls as a digital signal using an internet protocol (IP).  BT are marketing this as the introduction of their 21st Century Network and it is commonly abbreviated to 21CN.  More details about 21CN can be read on the BSIA website.

If you have installed digital communicators then this change may well affect you and your customers.

RISCO Group continue to work with BSIA and British Telecom conducting a series of tests on all RISCO Group products with digital communicator capabilities.

21CN update 9th Jan 2008
21CN update 3rd Mar 2008 - upgrade chips
21CN update 24th Sept 2009 - end-to-end delay
21CN end-to-end delay diagram