Oneway audio issue in Cisco 7925G wireless phones

[Shekhar Mahajan]

Given below is issue we are facing:

Phone A: Wireless G model
Phone B: Desktop 7975G model (CIPC)

When phone B calls Phone A, audio is not being transmitted to Phone A. Phone B is able to hear everything phone A says clearly.

But Phone A is not hearing anything (not even static). The only way to solve it is to disconnect the call again and again.

The issue occurs randomly and is not effected by whether the connection is showing full strength or less.The wireless phones have full coverage in most of the places in our office.

Could someone please guide us on how to go ahead and troubleshoot this issue.

Regards

[Leo Laohoo]

Can the 7925G make a successful call to an outside line? 

[Shekhar Mahajan]

Hi Leo,

Thanks for the reply. We are able to make the calls to the external or internal lines. The issue occurs randomly between the 7925G Wireless phones and CIPCs resulting in one way audio. But many users have raised the same concern over the past few days. Would be glad if you are able to help on this.

[Leo Laohoo]

The issue occurs randomly between the 7925G Wireless phones and CIPCs resulting in one way audio.

One-way audio always points to NAT mis-configuration.  

[kdavison007]

Are you running 8.3.121?  I noticed a very similar issue on a voice grade network in our test environment almost immediately going from 8.3.112 to 8.3.121.

[Rasika Nayanajith]

It could be CSCve20123. It is listed in TAC recommended code releases notes section under AireOS 8.3

http://www.cisco.com/c/en/us/support/docs/wireless/wireless-lan-controller-software/200046-TAC-Recommended-AireOS.html

Customers that use TSPEC (typically VoWLAN clients such as 792x, 882x, Spectralink), and deployments that use AVC traffic marking, should avoid 8.3.121.0 due to CSCve20123.  If such customers want to use 8.3, TAC can provide an 8.3MR2esc build with the fix.

Description

Symptom:
One way or no way audio is experienced. An OTA packet capture (unencrypted or decrypted) sees corrupt RTP packets - "bogus IP version 0" with garbled payload;
each corrupt packet is two bytes longer than expected.

Conditions:
Voice client does an inter AP roam while in call. CAC/TSPEC are in use.

Also can be seen if AVC marking is in use.

Workaround:
For lab testing, disable Fastpath on the WLC will prevent the problem.
(This is not an option for production deployments.)

Disabling CAC and disabling AVC marking may be an option if the design supports it.

Last Modified:

Jun 19,2017

Status:

Fixed

Severity:

2 Severe

Product:

(1)

Cisco 5500 Series Wireless Controllers

Support Cases:

2

Known Affected Releases:

(2)

8.3(114.45)

8.3(121.0)

Known Fixed Releases:

(3)

8.6(1.15)

8.5(1.158)

8.3(121.4)

HTH

Rasika

*** Pls rate all useful responses ***

[kdavison007]

Thanks!  I'll contact TAC as I'm pretty sure I'm hitting this bug.

[Leo Laohoo]

DO NOT, under any circumstances, load 8.3.121.4 (Escalation Image).  There is a strong chance this version will degrade your voice SSID.  

There are some discussions about this development HERE.