I previously had a PCTel HSP56 PCI modem in my Tapirex server for monitoring Caller ID, but moving the machine to a VMWare client made me look for alternatives after testing the modem with VMDirectPath and realizing it didn’t work with that modem (BTW, here are my Patched PCTel drivers that will enable CID if anyone needs it).

Now, after reading some forums it seemed the Zoom modem would work so I went ahead and ordered it from Expansys. I then attached it to my Silex USB-over-ethernet hub and mounted it on the Windows 7 client (all though the fact that it’s attached to a VMWare client in this way doesn’t really make any difference, it would be just the same scenario when plugged directly into a physical machine).

So, first off; enable CID on the Zoom. This is done by using a terminal program and sending the “at+vcid=1” command followed by “at&w” to save it to the modem firmware. Alternatively, it would probably suffice to add “at+vcid=1” to the “Extra initialization commands” of the modem (Device Manager->Modem->Advanced).

Now, this should be all but I still couldn’t get it to work. Since I’m using a VoIP box to push internet telephony into my existing phone lines, I do however have the possibility to fiddle around with the CID sequence that is presented to the modem a bit more than your average Joe. And behold, turns out the Zoom modem does not pick up on DTMF signals at all (this CID standard is used here in Sweden and other places as well). When it was changed to Bellcore (US, china, etc) the modem immediately picked up on the signal. Luckily for me I could change this in my PAP2 VoIP box, and it also turned out that my other CID enabled devices on the phone line could handle Bellcore. If you are not in the position where you can change this (ie. on a normal land line) and in a country that uses anything but Bellcore I guess you’re out of luck until Zoom fixes this in their drivers or firmware.

Here are the device settings for the Zoom modem in Tapirex:

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