Transferred calls can't be heard for 4 secs after transfer

[isdn3cxuser]

Hi,

We have 3CX V10 connected to a Sangoma A101 ISDN PRI gateway. When an incoming call is received and transferred to another phone in the company, there is a delay of between 2 and 4 seconds where the staff member cannot hear the caller (the caller can hear the staff member fine during this time). After that the call can be continued normally.

We are not using SIP trunks, it's all going over ISDN. Any ideas why this would happen?

 

[leejor]

Re: Transferred calls can't be heard for 4 secs after transf

Does the 3CX log (on Verbose) show anything?

 

[SY]

Re: Transferred calls can't be heard for 4 secs after transf

Could you please add information about the phones which are not hearing audio?

 

[isdn3cxuser]

Re: Transferred calls can't be heard for 4 secs after transf

Yes, they are Snom 821 and Snom M9 phones. Nothing shown on the logs that I can see. The Snom 821s are on the latest firmware. The M9s seem particularly problematic.

 

[farsight]

Re: Transferred calls can't be heard for 4 secs after transf

I have the same config except that I am using Grandstream phones. We do not have this issue.

Try calling from an extension to an extension then transferring to a third extension. If you don't have the delay then the problem is with the PRI.

Look at the codex selection on the PRI and on the phones. They should be the same but even if they aren't, you shouldn't have this much delay.

You didn't mention what you are running 3CX on. I ran on a VM for some time and found it less reliable.

 

[isdn3cxuser]

Re: Transferred calls can't be heard for 4 secs after transf

Fixed - I turned off the 'Supports Re-Invite' and 'Supports Replaces' option as advised by Sangoma and all is now well!

 

[SY]

Re: Transferred calls can't be heard for 4 secs after transf

Fixed - I turned off the 'Supports Re-Invite' and 'Supports Replaces' option as advised by Sangoma and all is now well!

Where have you changed settings? Was it the PSTN gateway (associated with Sangoma card) or the extensions (associated with Snom phones)?

Thanks

 

[isdn3cxuser]

Re: Transferred calls can't be heard for 4 secs after transf

It was in the PSTN gateway settings in 3CX. Worked perfectly from the moment I hit 'Apply'.

 

[SY]

Re: Transferred calls can't be heard for 4 secs after transf

It was in the PSTN gateway settings in 3CX. Worked perfectly from the moment I hit 'Apply'.

Thanks a lot for update