I worked for a company in the past that actually supplied VocalTec with a billing platform for their gateways. We also provided answer supervision hardware off of a dialogic platform. Being a Dialogic based software company we too were suprised they didn’t haven’t answer supervision in their gateways, since it’s a Dialogic Globalcall product. I know there were several companies back in the day (2+ years ago) we supplied our Dialogic based supervision platform to them that ran on VocalTec gateways. If they have today I don’t know. You may want to contact VocalTec directly. Tnet mostly deals in quintum hardware today, whereby their analog gateways have supervision built in. Otherwise I would look at Pleadise channel banks that can handle this supervision pretty much the same way Quintum does with thier analog units.
I hope this helps. let me know if you have more questions