About Speakerphone mode:

There is a TAPI method that can activate "Speakerphone mode" (which is always full-duplex) on modems that support it.

What "Speakerphone mode" actually does, depends on the modem and its drivers. Basically there are two different types of "Speakerphone mode":

- Some modems have a hardware plug where you can plug in a telephony handset (or headset). When you make a call through TAPI and activate speakerphone mode you can listen and talk to the other party in full-duplex

- Some other modems (often softmodems) support a software speakerphone mode. These do not have a hardware plug, instead they come with a driver that bridges the call to/from the soundcard. When you make a call through TAPI, you can talk and listen to the other party through your system's audio devices.

Unfortunately the Speakerphone mode is different from full-duplex line operation. Even when a modem supports full-duplex Speakerphone mode through software, that does not mean that you can achieve full-duplex playback/record through TAPI.

If at all, it works only with TAPI3. The Unimodem wave driver NEVER supports full-duplex line operation. (If you see that you have "Unimodem Full-Duplex Audio" driver installed, this means that your modem supports full-duplex speakerphone mode, not full-duplex line operation).

To see if a modem supports full-duplex line operation through TAPI3, you need to have a look for "LINESTARTDUPLEX" in the modem inf file. Please see UnimodemFullDuplexSupport for details.