Hi,
[CLIP elaborate description]
I think Wireshark is of limited use here. Things like MOS determination is
not in it's realm.
But it can be helpfull. I would go for test calls. Get down to the ends
where the "buzz" problem is happening and from there call into an
autoanswering upstream extension connected to a tone source. Capture the
RTP traffic with Wireshark once determined that the "buzz" occurs. Save
the payload of this capture and see what's made of it. If the buzzing is
in there, you've got issues with the PSTN/VoIP codecs, if it's not the
jitterbuffer in the terminals may be wacky.
Just my E0.02
Jaap