[cisco-voip] 7841 SIP Phone audio issues on some calls

[Daniel Pagan]

I would be interested in detailed CCM traces to answer a few questions... of the top of my head:

Is an MTP being introduced into this call? Do you have bi-direction comm with this MTP? I know you said other outbound calls are working but if the destination/dialed party is on the same provider network, the SIP capabilities are typically passed through untouched in my experience.

What is the SDP offer/answer look like from the perspective of the IP phone and CUCM? I would pay attention to the connection info (c=) and attribute (a=) headers, specifically looking to make sure an attrib header contains "sendrecv" or nothing with regards to direction (no directional attribute defaults to sendrecv). I'd be interested also in determining whether the receive packet count is increasing on the IP phone. If not, is the IP address in the connection info header an MTP? If it is, is the MTP at fault here? What does the SCCP statistics or RTP connection information show in terms of tx/rx media?

Is the issue only on 7841 SIP phones? Do you have other phone models running SIP firmware without this issue? If not, can you load SIP firmware and test?

Just thinking off the top of my head here. 

Thx

- Dan

-----Original Message-----
From: cisco-voip [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Erick Bergquist
Sent: Tuesday, March 10, 2015 9:20 AM
To: voip puck
Subject: [cisco-voip] 7841 SIP Phone audio issues on some calls

Anyone noticing problems on 7841 SIP phones when calling outbound with a SIP provider?

When we call Microsoft Conference bridge it connects but we can't hear the bridge.
It works fine from a SCCP phone on same Call Manager and same SIP trunk.
All other calls work on the 7841 outbound.

CUCM Version 10.5.1.10000-7

Firmware: sip78xx.10-1-1SR1-4

Thanks
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