[cisco-voip] Why is a transcoder getting involved?

[Dave Wolgast]

I have a semi-complex call flow which at some point, is invoking a
transcoding resource.  The problem is, I am not expecting to need a
transcoder in this situation, and it's exhausting my transcoder pool for
calls that actually need them.

Call flow involves a 3rd-party H.323 IVR behind an IP-IP-GW configured as an
H.323 GW with MTP in CUCM 4.1(3).  This was necessary because the IVR's only
useful transfer method is H.450.2, and we were able to use the IPIPGW to
convert that to something that CUCM could deal with.

PSTN --> MGCP PRI (3845 ISR) --> IP-IP-GW/hairpin (H323-to-H323) --> IVR -->
IP-IP-GW --> IP Phone (SCCP)

I believe that all legs of this call are configured for g.711ulaw, including
all dial-peers on the IPIPGW, which is why I don't know why the transcoder
is getting invoked.

The one thing I noticed, when looking at what the transcode resources were
doing, was the following:

#show sccp connections detailed
sess_id        conn_id       call-id    codec    pkt-period
type                bridge-info(bid, cid)     mmbridge-info(bid, cid)
117552198    -                 352499  N/A       N/A
transmsp         All RTPSPI Calllegs   N/A

117552198   126766065   352500  g711u    20
rtpspi              (255454,352499)         N/A

117552198    126766049  352498  g711u    20
rtpspi              (255453,352499)         N/A

-----------------------------
Not sure if this is relevant or not.

If anyone has any insight as to where the transcoder is creeping in, or can
give me a clue how to track it down better, I will appreciate it very much.

Thanks!!!
-- 
Dave Wolgast
Livonia, NY
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