In the great era of 90’s before VOIP technology we have some nice
videophones like Nexus
2000 and others. They
need only the pstn line, no isdn or other. Some question about them
° which protocol they use for video ? h323?
Very unlikely, since H.323 is a packet-based protocol, and analogue phone
lines are not packet based.
Bear in mind that the majority of these sorts of phones can only make video
calls to another phone of the same make, so the chances of reverse engineering
the call setup process, never mind the actual video streaming, are very slim
(in my opinion).
° is possible to use them on Asterisk on a standard analog phone card
(a400a for example)?
I imagine it might be possible, provided you use a high-bandwidth lossless
codec, although it sounds like a worse idea than trying to use a fax machine
through an ATA, and that can be pretty challenging.
Aside from the curiosity factor, what would be the purpose of trying to do
this, instead of using modern Internet-based video conferencing software such
as https://jitsi.org/ ?