Subject: [Megaco] Question regarding the Call Type Discrimination Package

From: [email-masked]
Date: Fri, 13 Dec 2002 16:11:27 -0600

Hi.

I am trying to understand better how the Call Type Discrimination Package
would be used by a pair of IP trunking gateways. I have focused so far on
T.38 and G.711 fallback but assume most of the logic would also apply to
data detection.

Can someone clarify for me the use of the calltyp property?  The property
description says it is used to "select the types of calls for which the
termination is monitored".  If the MGC sets it to FAX and DATA for example
what would be the expected behavior of the MG? Does this conflict or
somehow augment the MGC's ability to program the MG to report specific data
and fax call type discrimination events?

The package description talks about an exchange of signals "until the call
type is determined". Once the call type is determined, would the MGC set
the calltyp property to a single value, e.g. FAX or DATA?

Finally, is it valid for both the originating and terminating MGs to detect
and report all call type discrimination events that the MGC programs them
for? E.g. is it valid for the terminating MG to report CNG or for the
originating MG to detect and report CED and V.21 flags?

For the nonce, I have looked at the T.38 H.248 call flows but these use the
case of two MGs talking to the same MGC. The MGC detects fax signals and
plays them out on the opposite end MG. This would be analogous to
propagating fax signals through the signaling path between two MGCs (e.g.
using SIP). When I look at the Mule draft for SIP, it does no such thing.

Thanks,

John

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