WHY SOME CONNEXANT CHIPSET MODEMS HANG WHEN USED IN VOICE MODE?
Some Connexant chipset modems like the Zoom 3025C when used with the modem drivers shipped with the modem will hang when the AT+FCLASS=8 command is sent to the modem. As a result, the modem cannot be used in voice mode. Usually the modem driver causes this problem and a driver update will solve the problem. Please visit the modem manufacturer’s web site and download the newest modem drivers.