In order to give an example of why it is of importance for the MGC to know what type of modem connection that was activated, I provide a first draft of how text telephone support can be explained in H.gcp . In this case the modem will indicate V.18 usage, and that means that the media stream will be a T.140 text stream.
In the T.38 case it will be some kind of fax data stream, while for the V.90 case, I hope that the idea would be to use it for a PPP session to access the Internet.
So, these three modem types need quite different actions from the gateway and it need to be reflected in the MGC interface.
Please look in the attached proposed new section to H.gcp for further discussion and explanation.
Can anyone look into how to structure alternating between voice and text on the SCN side during a call and leading text to the text stream and voice to the audio stream on the IP side? ( called "voice over" in USA ) Can we support it?
Regards
Gunnar Hellström
At 11:05 1999-06-03 -0700, you wrote:
At 12:19 PM 6/3/99 -0500, Nancy-M Greene wrote:
Modem type: none, V.90, T.38, V.18, ... as applicable.
Why is this passed from MGC to MG? What does the MG do with it? Isn't this an MG capability? Maybe this is only useful for audit.
[[TomT]] This information is probably only useful for H.324 calls, although maybe it also applies to NAS operation. The MGC knows which modem type to assign based on dialled number, and passes the information to the MG to act upon.
Yes, this information is useful for NASes. In the SS7 case, the MGC knows which physical circuit the call will be completed on, and based on the dialled number, may have modem characteristics that need to be given to the NAS (MG) before that call is completed.
As has been discussed quite a bit before, this is AAA info and NAS's already have a protocol for that. We don't need to reinvent the wheel.
----------------------------------------------- Gunnar Hellstrom LM Ericsson
E-mail gunnar.hellstrom@omnitor.se Tel +46 751 100 501 fax +46 8 556 002 06