delayed call transfer

[mcnick50]

hello,

i have an installation v18.0 (Build 314) on premise windows server 2022 with 3 yealink t27g and 5 t31p. when i transfer call from one ext to another ext i have about 5-10 sec delay before it starts ringing. no network overload. router mikrotik crs328-24p

 

[JohnS_3CX]

Hello,

1. Are all the phones on the same local network and subnet as the 3CX machine?

2. Is the Windows server used for other things or dedicated to 3CX?

3. Can you tell us what CPU it has, and how much RAM?

4. Does the delay happen only when transferring external calls, or with internal calls too?

 

[mcnick50]

1. all phone are local same subnet
2. only 3cx
3. intel core i3 4330 and 4gb ram
4. both internal end external calls

 

[JohnS_3CX]

Hello,

Hmm.. given the age of the cpu and low ram, I think you might not be able to avoid some delays in general.
https://www.3cx.com/docs/recommended-hardware-specifications-for-3cx/


But I think you would greatly benefit from formatting the machine and installing our Debian ISO which uses a lot less resources than Windows, and will free the CPU and RAM capacity to make it available for your calls.

Take a look at out guide and consider switching to Debian if you will keep 3CX on this machine:
https://www.3cx.com/docs/manual/installing-debian-linux-pbx/

A 3CX Windows version backup can be restored on a 3CX Debian version.

 

[mcnick50]

it's not the cpu and ram. i have the same cpu and ram on other installations with no problems.

when restarting the ip phones... everything works ok for a while

 

[JohnS_3CX]

when restarting the ip phones... everything works ok for a while

If this always fixes the issue, then there may actually be something else causing the problem.

As a first thing, can you please check whether all the phones use the firmware that appears on this page?
https://www.3cx.com/support/phone-firmwares/

 

[mcnick50]

yes all devices have the firmware as on the link above

 

[JohnS_3CX]

Phones usually tend to become slow to react when

a) they have a large amount of contacts (ie. 1000+)
b) they have a large amount of BLFs to monitor (30-50+)
c) if there is something on the network causing a delay (i.e a "broadcast storm")
d) There may be a rogue DHCP server on your network

So a) and b) are easy to check of course, do you also have a way of checking c) and d)?

This might be a difficult one, but it most definitely is one of those problems that could go away by regularly restarting the phones. It will always come back after a while, but restarting the phone frees up memory and forces DHCP registration again buying you some time until the next incident.

 

[mcnick50]

a) no contacts on ip phones neither pbx
b) 5 blf only on the 3 t27g
c) i have no network delays...
d) i have cheked that nothing suspicious

 

[JohnS_3CX]

Are you familiar with Wireshark?

 

[mcnick50]

not really

 

[Alphabetic]

Can you try doing a test between 2 clients either on mobile app or web client?

 

[mcnick50]

Can you try doing a test between 2 clients either on mobile app or web client?

i'll try tomorrow and tell you

 

[mcnick50]

no problem on mobile app

 

[JohnS_3CX]

Hi,

Since the app goes via internet, this is more evidence that the delay may be on the local network then.

We have not ruled out network delays / routing issues yet, this needs to be investigated further so it can be ruled out.

You could use the help of an experienced 3CX Partner to run packet captures on the phones, PBX and network, then compare them to check the delta between the time a SIP signal is sent, and when it was received, and when the reply came back to the PBX. This will clearly show what is causing the delay, and it could be single thing or a combination of things working together and adding up delay to the point that it becomes noticeable.

3CX Partners in your area may be found here
https://www.3cx.com/ordering/find-reseller/