3CXPhone and OPAL (Ekiga) one-way audio

[RomanSk]

Hello All,

I got problems with OPAL/SIP and 3CXPhone - when calling from OPAL to 3CXPhone audio is only one-way.

The problem is that 3CXPhone doesn't understand 101 format at beginning of m=audio:

m=audio 5000 RTP/AVP 101 3 0 99 98 2 97 108 96 7 100 114 104 105 106 102 103 107

But correctly processes:

m=audio 5000 RTP/AVP 3 0 99 98 2 97 108 96 7 100 114 104 105 106 102 103 107 101

I would assume that this is 3CXPhone issue.

Regards,
Roman Skvirsky

 

[SY]

Hello All,

I got problems with OPAL/SIP and 3CXPhone - when calling from OPAL to 3CXPhone audio is only one-way.

The problem is that 3CXPhone doesn't understand 101 format at beginning of m=audio:

m=audio 5000 RTP/AVP 101 3 0 99 98 2 97 108 96 7 100 114 104 105 106 102 103 107

But correctly processes:

m=audio 5000 RTP/AVP 3 0 99 98 2 97 108 96 7 100 114 104 105 106 102 103 107 101

I would assume that this is 3CXPhone issue.

Regards,
Roman Skvirsky

Note, it is forum of 3CX PhoneSystem.

Anyway, what is a "101 format" and how to understand it correctly?

Thanks,
Stepan

 

[RomanSk]

Hello All,

I got problems with OPAL/SIP and 3CXPhone - when calling from OPAL to 3CXPhone audio is only one-way.

The problem is that 3CXPhone doesn't understand 101 format at beginning of m=audio:

m=audio 5000 RTP/AVP 101 3 0 99 98 2 97 108 96 7 100 114 104 105 106 102 103 107

But correctly processes:

m=audio 5000 RTP/AVP 3 0 99 98 2 97 108 96 7 100 114 104 105 106 102 103 107 101

I would assume that this is 3CXPhone issue.

Regards,
Roman Skvirsky

Note, it is forum of 3CX PhoneSystem.

Do you recommend me to post 3CXPhone issues to Ekiga maillist?

Anyway, what is a "101 format" and how to understand it correctly?

Thanks,
Stepan

101 format is SIP telephony event specification. When is it first preferable in the audio specification - 3CXPhone doesn't open audio for receiving.
When first preferable is any audio format like 3 (GSM) or 0 (PCMU) it works OK.

 

[SY]

Yes, I recommend you to ask Ekida support about issues related to 3CX phone. If they don't support it, then choose proper "softphone" for your OPAL PBX.

Also,
check RFC 3261 and 3264. There is lot of information.
Legacy version of 3CXPhone, you mentioned, has some issues related to SDP negotiations, but you still can configure it to work with any PBX.

P.S. Try to use 3CX PhoneSystem instead of OPAL. May be you will find it useful.

 

[RomanSk]

Yes, I recommend you to ask Ekida support about issues related to 3CX phone. If they don't support it, then choose proper "softphone" for your OPAL PBX.

Also,
check RFC 3261 and 3264. There is lot of information.
Legacy version of 3CXPhone, you mentioned, has some issues related to SDP negotiations, but you still can configure it to work with any PBX.

P.S. Try to use 3CX PhoneSystem instead of OPAL. May be you will find it useful.

Ekiga, SY, Ekiga.

I have issues with 3CX Phone not only with Ekiga, but with several other SIP clients. And the problem is not in those clients, but in 3CX Phone. I even perform 3CX work to find out the root cause.

Frankly, I am not happy with your reaction - my goal was to make 3CX system more compatible with existing SIP environment.

And I am 100% sure that there are PBXs with which 3CX Phone is not compatible due to implementation issues of 3CX.

Following the above I can't recommend 3CX for my clients.

 

[SY]

Roman,

Sorry for misprint, sure it is "Ekiga".

I just informed you that 3CX PhoneSystem is not related to 3CXPhone.

In some combinations, 3CX phone can produce asymmetric RTP streams (means different codecs will be used in different directions). In some cases it produce problems if other party of call doesn't understand it.

You also found additional problem , but you have workaround - just put telephone-event to the end of payload list. It will resolve problem.

Anyway, if you put telephone-event on the top of payload list then it looks very interesting from RFC point of View:
RFC3264 last paragraph of page 11.

The answerer MUST send using a media format in the offer
that is also listed in the answer, and SHOULD send using the most
preferred media format in the offer that is also listed in the answer.

In your case - telephone-event is most preferable format

Thanks for you attention and sorry if I said something roughly
Regards,
Stepan

 

[RomanSk]

OK, thanks.
Then I hope that 3CX Phone developers reach this info.