The D-channel is the third ISDN2 channel, normally used for signalling and running at 16Kbps. It is permanently online to the exchange, compared to the B-Channels which go on and offline like a conventional line. The D-channel can be used for low volume data transfer and BT's service allows a 2400bps permanently connected channel to a remote location. This might typically be an ISP and be used for checking for email or incoming web server requests which can in turn trigger a dialback call on the B channels. The D-channel link is connected permanently to the single destination.
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For a breakdown of the charges, click here . ADSL started trialling at the end of 1998 and will be launched across the UK at some time in 2000. Click Here . We supply a complete range of ISDN equipment including TAs for data, Routers for Network connectivity and also PBX office systems. We can advise you on what equipment will be best for your purposes, and once you have it, we'll be here to offer you after-sales technical support.