It will still require some intelligence from the VoIP system, eg to switch off jitter adaptation, and a good path with little packet loss. The equivalent to T.

It will still require some intelligence from the VoIP system, eg to switch off jitter adaptation, and a good path with little packet loss. The equivalent to T.38 for data modems was ITU V.150.1 , but I get the impression that it wasn't implemented much.