Toby Nixon asks if there really is a need for a simple logical channel approach for text chatting with T.140 in H.323, or if we could do with the T.120-based T.134 solution for all H.323 implementations.

If you remember how this started in March in Geneva, I came in with the view that the T.120 solution for text conversation would mean maximum compatibility for least work. However, first recations came from the H.324 side, asking for a simple solution in a logical channel. Then, in the Herliza meeting, apparently text chatting was discussed in a group that was aiming at the simple Internet Phone applications, who said that there should be a similar solution in H.323 if I wanted full coverage in H.323 products.

I agree that it complicates the implementations to have T.120 as the solution to invoke if we turn out to enter a multipoint situation, and otherwise use plain H.323 data channel for point-to-point.

It is easy for Toby to say that T.120 should be the base. He usually has enough power and memory around. I would like to get the view from Internet Phone people as well. If this is the text telephone of the future, it should be suiable to attach to any implementation of voice and video telephony.

On H.320 dedicated simple videophones, it seems to be common to have a connector that can be used for T.120 application attachment. Can that be the way to add T.120 to Internet phones also?

A summary of Sunriver activities in the text chat area: -A general purpose character by character text chat protocol based on Unicode was determined, named T.140. -A way to carry T.140 in a simple T.120 APE was determined, named T.134. -A way to carry T.140 in a simlpe H.324 logical channel was edited into H.324 and H.245. -V.18 - the PSTN text telephone modem - was changed to point at T.140 instead of having its own presentation layer. -Work was initiated to define a way to carry T.140 in a simple data channel in H.323 - H.245 - H.225.0

If you want to take a look at T.140 and T.134, they are available in http://www.pi.se/~omnitor/standd.htm

Can all H.323 producers have room for T.120LITE and T.134 ?

Best regards Gunnar Hellström

------------------------------------------------ Gunnar Hellström Omnitor Alsnögatan 7, 4tr S-116 41 Stockholm SWEDEN

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