Problem with DTMF SIP INFO

[David.BOUVIER]

Hello,

I have a problem with the DTMF SIP INFO Method. when I make a voice call between two softphone, during the voice call if I try to send a sequence of DTMF (for example #987*) for the first softphone (extension 900) to my second softphone (extension 001), the sequence is not fully received, only the first DTMF is received.

I have made a wireshark capture on the server and I can see that the server has well received the DTMF sequence but the server has not forward the sequence to my seconde sofphone, only the first DMTF has been sended

Have you an idea how i can resolve it ?

Thank you for your answers

David

 

[eddv123]

Hi David,

Try using DTMF using INBAND RFC 2833 instead, this will send the DTMF in a separate RTP stream (instead of in the actual RTP stream like classic INBAND).

SIP INFO DTMF sends DTMF as SIP packets and as it is send separate to the RTP traffic can have synchronization issues.

Perhaps also check that your machines running the soft-clients are not running Windows Firewall and thus blocking the traffic being sent.

 

[David.BOUVIER]

Hi

Thank you for your answer.
I can not use the RFC2833 because my softphone accepts only the SIP INFO method.

The problem is not a firewall, because in my wireshark logs directly on the SIP SERVER (on cloud), i can see that all the DTMF are well received from my first softphone but only the first is well forwarded to my second sofphone

 

[eddv123]

I presume then that you are not using 3CX Phone for Windows etc in that case ?

If that is the case then I would strongly advise that you do, as the 3CX soft-phone supports all 3 methods - in fact if the device does not support RFC 2833 then it is out of spec of the SIP standards most devices and providers adhere to.

 

[David.BOUVIER]

Yes, my second softphone is not a 3CX phone and I know that it is not standard to only support one method but it does not explain why my SIP server forwards only the first DTMF and not the others during a voice call.

Thank you for your answers

 

[eddv123]

No it does not answer the question. I guess the key question is at what end is the issue occurring - if you use 2 x 3CX soft-clients do things work OK for SIP INFO ?

What brand of soft-client are you using ? Bria, Media 5 fone ?

 

[David.BOUVIER]

I will try to establish a voice call between two 3CX softphone and check on the server if the DTMF are well forwarded in order to see if the problem is in relation with my second softphone