Incoming Calls Ring and Keep Ringing, sometimes

[Dynamic Networks]

At random times in the day, a call will come in. All destination phones that should ring do ring. However, when anyone picks up any phone, the phone they pick up as well as all other phones continue to ring. The phone they pick up will have no call on it. If they hang up. the call continues to ring until the timeout.

The caller hears all the normal things they should: ring progress tones, voicemail playback when it times out, etc.

Outgoing calls never have any issues.

System Details Follow
3CX Version 16.0.8.9 Pro
Phones: mix of Yealink SIP-T276 and SIP-W60/56 - Firmware all up to date.
SIP Provider: Wiretap Telecom
All phones are local to the PBX, same building, same subnet, same switch.
Firewall test passes.
Call Route: Sip Trunk => Call Flow App => Queue

The Call Flow App does different things depending on time of day, day of week, and in/out of office status.
I have confirmed that bypassing the Call Flow App does not affect the problem.
I have also routed calls directly into a ring group instead of a queue. This does not affect the problem.

Call Log: shows the call, shows that it's been answered by one or another extension.
Event Log: shows nothing but typical register denials and blacklists from outsiders.
Activity Log: shows nothing out of the ordinary. (Shows only the typical 487s, and the occasional authentication failure from an outsider).

Anyone have any advice they can point me towards to diagnosing this issue?

 

[AWS2P]

did you made a call try without your CFD file to see if behavior stay the same or become normal?

 

[Dynamic Networks]

did you made a call try without your CFD file to see if behavior stay the same or become normal?

I noted that in the original post. If I bypass the CFD entirely and send calls straight to a queue or a ring group, the problem still occurs.

 

[AWS2P]

to isolate from sip trunk, if you call internally Q number from an extension out of Q agents , do you get the same ?

Are your phones on a POE switch ? is it enough budget?
How many phones connected to your DECT base? which audio codec do you use ?

 

[Dynamic Networks]

to isolate from sip trunk, if you call internally Q number from an extension out of Q agents , do you get the same ?

Are your phones on a POE switch ? is it enough budget?
How many phones connected to your DECT base? which audio codec do you use ?

The issue is sporadic. Calling the queue internally has not yet caused the issue. (The issue also occurs if calling a Ring Group with the same phones in it, so I'm certain it's not a Queue problem.)

All phones are on a PoE switch, and the budget is fine.

There is one base that supports eight phones. It has five phones connected. The audio codec is the default, whatever that is. I don't currently have access to the phone system to confirm the codec.

 

[AWS2P]

Are the 8 phones on DECT base W60B all in that same Q ? because on W60 there is 2 limitations, even if you can have 8 phones not all are able to be in call in same time. Also depending on audio codec used (if width band like G722) it may be only 5 phones able to call simultaneously.

 

[JohnS_3CX]

Hi,

Have the 3CX guides been followed? If not I would start from scratch following the guide.
https://www.3cx.com/sip-phones/

Are custom templates being used?
If yes, then remove them and provision the phone normally to see if this corrects the behavior


Once the above has been confirmed, if the problem persists then it would appear you may be dealing with a network issue. If the phone picks up the call but the PBX never received the "reply" then it will continue to tell your phones to ring.

 

[Dynamic Networks]

Hi,

Have the 3CX guides been followed? If not I would start from scratch following the guide.
https://www.3cx.com/sip-phones/

Are custom templates being used?
If yes, then remove them and provision the phone normally to see if this corrects the behavior


Once the above has been confirmed, if the problem persists then it would appear you may be dealing with a network issue. If the phone picks up the call but the PBX never received the "reply" then it will continue to tell your phones to ring.

The guides have been followed (always!)
No custom templates are in use. (never!)

Network issue was my guess, was just looking for some general consensus on the issue.

 

[JohnS_3CX]

I think for your case you will have to run some captures (on phone and PBX) to see where the phone sends the "200 OK" and if it is reaching the PBX. Depending on what you find you might have to make network adjustments, or you might need to escalate the case to 3CX Support.