old DialUp modem with "voice" capabilities

[Gianni]

I'm trying to use an external dialup modem (with Voice capabilities. that is declared as Data/Fax/Voice) to let it dial a telephone number and send a voice message to the called party.
While it's very easy to dial the number, I'm not been able to send the voice message over the line despite the command sequence seems to be correct.
Without entering in what I've tryed so far,(just various AT commands settings). I'm asking if someone already had experience in that stuff.
The modem that I'm using is an external modem connected to COM1 that has an Cirrus Logic chipset CL-MD56XX.

Here are few links where I'm relying on:

http://bytes.com/topic/net/insights/703378-how-play-wave-file-phone-c-part-i part-ii  part-iii

here an Interactive Voice Response System & related Perl module

Thank you