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BYE Q.850;cause=16

LukasH

January 08, 2022 17:23

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P560 and Yealink T21E2 Phones. A lot of them in three different locations. From time to time, mentioned error occurs durring call. 

Phones losts calls with this error code Q.850;cause=16. This is displayed on phone. There is BYE on P560. Nobody quits the calls manualy, of course. And for some time, this phone device cannot make another call. Nothing like this happens in same locations with different PBX. 

We are trying to found problem with Yestar also, but it could be good to make this public, if someone is facing same problems. And this problem is big trouble for us. Because our customer makes 50k calls during one month. 

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7 comments

• 0
  
  Eric Jiang January 10, 2022 05:48

  Hi Lukash, do you contact our support engineer to check this issue?

• 0
  
  LukasH January 10, 2022 07:26

  Yes, we did. 

  It is in process. But first information from you is that BYE is from Phone. It is all very weird. 

• 0
  
  LukasH January 10, 2022 11:44

  It is not for sure now, but it seems, when we move customer from P560 to YMP, there are no such problems. 

  Also note, our P560 is equiped with D30 module. 

• 0
  
  Sandro Oliveira January 12, 2022 12:27

  Hello LukasH,

  Add this line to your Yealink phone provision and you won't have that problem anymore:

  sip.call_fail_use_reason.enable=0

• 0
  
  LukasH January 12, 2022 12:38

  Thank you Sandro, but it is only cosmetic patch. Isnt it? 

  We have also observed, when wrong number, or DID, or busy number is dialed, it seems like hangup from PBX, but without tone, without info, nothing. Or only code 850. So calling party is confused. 

• 0
  
  Sandro Oliveira January 12, 2022 12:54

  The cause codes are always sent through SIP Signalling:

  https://www.dialogic.com/webhelp/msp1010/10.2.3/webhelp/MSP_DG/ISUP/Cause_Codes.htm

  What that line does to Yealink phones is to turn off displaying the error codes. It will also make the phones display a human readable message instead, like "Busy" or "Not available".

  So I guess yes, it is a "cosmetic" thing to see a human readable format instead of a code the users can't understand. I honestly never understood why Yealink has that setting by default, it should be disabled.

  EDIT: this is going to resolve your Q.850 error codes displayed on the phones but not your actual problem, which is the calls hanging up for no reason, you should take a pcap and see why. Is the call really estabilished? Or it hangs up before answering?

• 0
  
  LukasH January 17, 2022 12:29

  Sandro, thank you, it was very helpfull. 

  It solved a lot of trouble tickets and it helps us to focus on different problem. 

  Some older Yealink phones are a little bit stupid in this area. T21 E2 IP for sure. T26 or T3x do not produce this problem. 

  Here is more about it: https://support.voipcloud.online/hc/en-us/articles/360001517496-Manual-Configuration-of-Yealink-IP-Handsets#heading-5