Lost audio when answering a call between two T54W phones

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(08-02-2019 06:08 PM)complex1 Wrote:  Hi,

In your test I miss 1 test... a call from a T42S to T54W.

Please try the T54W to T54W test again but now use codec PCMA or PCMU only and see if it happens again?

BTW: do you make use of a PBX?

We can reproduce the issue using a T54W to T54W using G729, PCMA, PCMU, if you answer and count 1, 2, 3 you will hear 2 or above. Using a G722 you always hear 1.

Worth noting in the earpiece you can also tell the RTP hasn't established yet either.

If using a T54W and a T42S all codecs work, you will always hear "1". This seems to point me in the direction of a T5X issue.

All tests performed using Ethernet, have tried PoE and Power Supplies.

The PBX is FreeSWITCH 1.8 and we've also tried 1.6 to ensure it isn't anything on FreeSWITCH.

@Yealink - The latest firmware was released in April, is there a T5X SIP BETA firmware I can get access to and see if it is a bug that has been addressed.

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(08-02-2019 08:55 PM)jolouis Wrote:  Also are you running the T54W over wireless or on a wired connection?

I have a T53W, T54W and T57W here at my disposal so if you give me details I can test and try to investigate also.

I can PM details to our servers if you like for testing but if you were to do the following my theory is you should be able to reproduce:

- 2 x T54W running firmware T54W-96.84.0.30.rom
- Factory reset the phones and setup the basics to register to a PBX
- Remove all Codecs and have G729 as the only listed codec
- Dial from Extension A to B, Answer B and say 1 2 3 4 and see if you hear 1

The configuration we are using is this:

- PBX is hosted on a public IP in an external data centre
- The two test phones are behind a NAT router connecting to the PBX on the public IP

I will try the same test today using a PBX on the same network segment as the phones just to confirm it isn't a NAT based issue, but as we don't appear to see the issue on T4X, T3X, T2X phones I don't think this will be the issue.