The Vox-O-Mat Telephony Gateway

The Vox-O-Mat Telephony Gateway is currently available for Win32 platforms.
The minimal configuration use a standard 16 bit full duplex sound card and a standard voice modem (at any baud rate) with speakerphone function. Later versions will handle high-end telephony interface boards as well. It can handle the incoming calls or dial out through the telephony network.
On a dial-up configuration it waits for the incoming ring. When a phone ring comes in, it answers the call, plays greeting or error messages, collects the caller information and password if needed, and the dial number. It searches the called party throughout the Vox-O-Mat Server, connects to it and rings it. After the call is completed, it hangs up the phone and waits for the next incoming call.
On a dial-out configuration it will wait for any call request from the Vox-O-Mat Server. When a call request arrives, at first it checks whether the number is allowed to be dialed or not. If the number is not blocked, the gateway tries to dial through the telephony network, and sends the call status to the caller.
The two working modes can be set together, of course, but when it accepts an incoming call, the gateway will send a signal to the server, so the server will not route calls to it before it finishes the current call.
The gateway collects DTMF codes throughout the call and transmits them to the other talking party where the DTMF codes are generated, so the dial tones will not be lost during the transmission. That is why it can be used to access voice mailboxes, information systems as well.