Modems with Caller ID in the UK

Modems with Caller ID in the UK

If your telephone company uses the Bellcore CND system, you can use any of the American Caller ID modems. However, if you need BT Caller ID, your modem options are limited to Hayes and Pace. The new Aztech 56K modems are reputed to support CLI.

Problems with Hayes modems include polarity sensitivity and insufficent sensitivity to the Caller ID signal. Increasing the gain on the line may help, as can tweaking the hardware, but there are no guarantees it will work. These problems have been compounded by ambiguity over which modems are Caller ID capable and which are not. Only the Voice models of the Accura 336 have Caller ID, of which the external ones are more reliable. Only the Message versions of the 56K Speakerphone model have it, as do 56K internal models with "A" serial numbers, but not "L" serial numbers. It works on an Accura 288 Message modem. The firmware update may help if your Hayes modem does not detect polarity. For troubleshooting read these posts.

No 3com/US Robotics modems are known to support BT Caller ID.

Apparently Caller ID is a standard feature on ISDN terminal adaptors, but only a handful send it to their POTS ports, allowing you to plug in a box directly. Network Alchemy products are the only ones that support the BT standard. The Zyxel TAs pass it as well, but I think they use the Bellcore standard and the data appears in a slightly different format. http://www.adelheid.demon.co.uk/pgs_isdn.html has details of lots of ISDN hardware, and a good bit about the nightmarish BT implementation of ISDN. For instance, it seems that BT's interpretation of ISDN-2e can't distinguish between WITHHELD and UNAVAILBLE, which makes quite a difference for ACR fans.

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