Martin, Many thanks for your reply. I have followed your supplied ink to read up on using the "AT" command set to control a connected modem. I found that in order to send an announcement ie. "Hello Thank you for calling . ." . etc. to the person calling, the modem must first be set to voice mode. The sound file is then sent as a byte stream which is converted back by the modem into audio signal and sent down the phone line to the caller. First problem is that the sound file must be in a format which the modem can handle. Secondly all zero bytes in the stream must be sent twice or else the modem will consider a single zero as an EOF signal and conversion / transmission will end. So it seems I must experiment further - probably principally using the _CommSendByteArray from your UDF. I will post progress reports here - if any! Regards, Rod