Very long delays when phoning internally on 3CX

[Avanine]

Hi all

Please could you kindly assist and diagnose where the issue might be for the very long delays before the phones actually ring when phoning internally on the following 3CX / Debian Linux Server
It takes roughly 15-20 seconds before the phone that is dialled actually starts to ring, and in your ear on the dialling ext.
All the phones in question are desk phones (Yealink T23G’s and Yealink T27G)
This is a very recent migration from a Windows VM to a Linux VM – this problem was also not experienced before the migration.
All the Phones have also been upgraded to the most recent firmware available as per 3CX’s recommendations in attempt to try and resolve this very issue.
when pinging the 3CX server the times are sub 30ms so i doubt its bandwidth (breakout is on an LTE solution) this accurs when there is almost zero traffic traversing the LTE


Regards

 

[JohnS_3CX]

Hi @Avanine

Please provide info on your installation as per this post: https://www.3cx.com/community/threads/information-to-provide-when-requesting-help.67558/

Additional info: who sits behind the LTE solution

 

[Avanine]

Hi
Details as needed

• 3CX Version, e.g. Enterprise Annual 16.0.504
• Server OS, e.g. Debian 9
• Is the 3CX Server Hosted and where? Yes - ICT Globe
• IP Phone Make/Model/Firmware - Yealink T23G 44.84.0.95 / Yealink T27G 69.84.0.95
• Provisioning Method: STUN
• Trunk Provider or Gateway Make/Model - Trunk Provider - Dataphone
• Has the Firewall Checker passed: YES
• Are custom Phone Templates being used: NO

Additional info: who sits behind the LTE solution - Telkom = LTE Provider

 

[JohnS_3CX]

Ok if the phones are STUN and sitting behind the LTE, then there may be delays as well as issues with SIP/RTP ports (LTE networks usually have carrier grade NAT that can mess with your SIP phones).

You can try to "hide" the traffic from the LTE provider using a 3CX SBC which should also provide encryption and easier phone provisioning as well as keep traffic from calls between extensions locally, saving you some bandwidth.

However, if the delay of call establishment is because of the LTE link, an SBC might not improve the situation. It's a good solution to try though since we don't know how the LTE network is set up in the provider's core network.

 

[leejor]

You could make a test call, making note of the start time (last digit dialled). then check the 3CX Activity Log to see how long before the call reached 3CX and how long before an Invite was sent back out. Do your sets use a dialplan, to send valid digit strings immediately, or do you rely on an end of string key?

 

[Avanine]

ok..

what we tested now is i got the client to download the 3cx app to their phone.
i provisioned it to be the same ext as his deskphone.
i then got him to make a call to the deskphones in the office from his mobile 3cx app when connected to the WiFi network and also do the same when connected just to his mobile network.
either way when he makes a call it rings at the deskphones or 3cx app as it should taking just a second or 2.
however... when he uses hes deskphone to make a call to any of the ext's, be they on the 3cx app or deskphone... it still has a very long delay before it rings, so its only happening when the calls are made from the deskphones.
there are no firewalls in place on their existing network.

regards

 

[Avanine]

Also....
ive reset all the phones to factory defauly and re-provisioned them via stun.
still does the same.

ive also run a continuous ping to the 3cx from the deskphones and the times are more than adequate with no drops at all.

 

[leejor]

Compare the 3CX Activity Log, for a call from each type of device. How long does 3CX take to handle each call? It may be that the desk set is not sending the digits immediately.