This one is a longshot but I'll give it a try anyway.
I recently bought this USB Telbox device (AKA yealink USB-B2K). It's a device that connects to a PC over USB and to the PSTN (home telephony) and regular phone device over RJ11 cable. The device is used to direct incoming PSTN calls to the skype client running on the PC and to make calls over skype by simply dialing the keypad on the regular phone device.
This is all nice, but I was wondering if it would be somehow possible to use this device to make calls from the PC over PSTN. Now, the device can make PSTN calls when dialing on the regular phone's keypad (hitting '*' on the phone's keypad make it switch from calling over skype to calling over PSTN). My question is whether it would be possible to control the device from the PC over USB and make it make a call on the PSTN.