3CX shows SIP trunk up and running but I can't make a call

[topdata]

Hi,

I have a strange problem. I have the latest version of 3CX standard and it is running as it should according to my dashboard. The SIP trunk is up and the phones are registered. But once every few days I can not make a call. I pick up the handset, dial a number, but the phone stays silent. No tone what so ever.

The only way to fix this is to reboot the 3cx system and reprovision the phones again. So my questions are:

- What is causing this behaviour? Can I prevent it from happening or check something with a tool and restart a service automatically when this happens?
- If the 3CX system reboots after for example a power problem, nobody can use the PBX anymore because the phones aren't registered. How can I make sure that the phones are registered again automatically if they become unregistered?

Hope somebody had this problem too and knows how to fix it.

Best regards,

Stef

 

[YiannisH_3CX]

Hello @topdata

It sounds like your issue is that the phones are loosing registration and do not re-register. When you cannot make a call are the phones registered? do they appear in the management console of the PBX under the phones tab?
also what phones are there and how are they provisioned? Are these local extension or remote? Manually or PnP provisioned?

 

[topdata]

Hi,

No the phone is registered. It is listed under the phone tab. It's a snom D375 and just a local extension. They were PNP provisioned. When I reboot my 3CX system I also have to reprovision the phone. I am doing that with **## which starts the reprovisioning on this phone.

In the "no calls possible" situation I also tried reprovisioning the phone without rebooting the 3CX system. That solves nothing. So the problem is in the PBX and not in the phone probably.

Regards,
Stef

 

[online8]

Hi,

No the phone is registered. It is listed under the phone tab. It's a snom D375 and just a local extension. They were PNP provisioned. When I reboot my 3CX system I also have to reprovision the phone. I am doing that with **## which starts the reprovisioning on this phone.

In the "no calls possible" situation I also tried reprovisioning the phone without rebooting the 3CX system. That solves nothing. So the problem is in the PBX and not in the phone probably.

Regards,
Stef

Stef,
Can you please confirm that the public ip address isn't changing? In other words, does your internet connection have a static address? I know that you may only be making local calls but this could be the cause of the issue. Also confirm that the dns server that the 3CX server points to i running and that the phones and the 3cx server all point to the correct dns server.

 

[n2]

The indication that the phone is registered within 3CX is not necessarily an indication that the phone thinks that it too is registered. The registration is initiated by the phone with a request. When seen by 3CX it will go through a set of messaging back to the phone that will ultimately end with 3CX binding the registration with the associated response back to the phone. As a result, 3CX assumes the registration has occurred, but if for whatever reason the phone did not see the messaging....it may not be registered. 3CX will continue to show the phone as registered until such time as the expiry period is reached. It is at this point that 3CX is once again expecting the phone to start the process over.

The reverse is true as you noted when 3CX reboots. As the phones are likely working off of the last registration period, they think they are still registered and will make no attempt to re-register until the current expiry period and renewal come about. As 3CX does not know about the phones after the reboot, it sits waiting for the phones to re-register. Depending upon the registration interval and when the 3CX system is rebooted and back on-line, the time is variable as to when the phones will come back. Rebooting the phones may simply accelerate the registration process; otherwise just by waiting....the phones should come back of their own accord.

When the issues occur, log into the phone web interface and examine the status and see what it thinks with regard to the registration. You should also be able to see the registration period....and, I assume, it could be as much as an hour. You should also be able to see the SIP server settings and other setting so as to insure all is correct. Rebooting 3CX and/or the phones or forcing a re-provision is only masking the issue by fundamentally re-setting everything to square 0.

It was not clear if the issue of not being able to make a call is only associated to your phone or to any others, if all phones are the same make and model, if remote or on the same LAN with 3CX and if the phone(s) have the latest approved firmware.

I am uncertain as to what the registration period is that 3CX uses for extensions. I have not really gone into it, but I do see some posts where others have indicated various times...the most common one being 300 seconds. I guess I could wireshark it, but you might try looking in your phone and setting the period from its current setting to something like 120 seconds and see. Additionally, there maybe some settings for retry in the phone which is a setting that the phone will use in the event the expiry has occurred and the phone sent a register request and did not successfully complete the transaction. The phone should re-attempt the registration request within this interval. Finally, be advised that even setting the registration period to something within the phone is not a setting that has to be honored by 3CX. The server determines the period and can/will be the one that sets the period. It may take the setting as a suggestion and may honor it, but is not obligated to. The reason for this is to prevent folks from putting in registration periods that might cause unwarranted traffic and make the system go through processing that it should not need to. In other words, if you have a network that needs a registration period so small as to keep everything running smoothly, then you have bigger issues as hand.

 

[leejor]

Check the 3CX Activity log right after a call attempt. This will tell you what the PBX is receiving, if anything. It will also show if there is a Codec issue (the silence is a bit perplexing). From my experience, many devices will place a call without registration, unless it is optioned, in the device, to forbid this. Of course you won't receive calls without registration.