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Occasional Advisor


Hi I am troubleshooting a DTMF issue on a 3.1.2 HDX8000 and was not able to see DTMF signal on packet capture coming from the HDX, can someone tell me if signalling is in band for H323, I think I remember on older versions I was able to see them in H245 stream.

Message 1 of 4
Polycom Employee & Moderator

Re: H323 DTMF

Inband audio is used in H.323, H.320, POTS and ISDN voice.  RFC 2833 is used in SIP calls.

Message 2 of 4
Occasional Advisor

Re: H323 DTMF

Hi appreciate the prompt reply. Thank you.

Message 3 of 4
Occasional Visitor

Re: H323 DTMF



Is there any difference in between endpoint types and and software versions?


Also are there any versions which support other methods on h323 than inband?

(like RFC2833 or H.245).


If using polycom infrastructure and interworing the call to sip, can they translate DTMF?


At least we face issues with unregistered polycom endpoints calling through a Cisco VCS 

doing interworking to a sip trunk which only supports SIP-RFC2833 based DTMF.


Is there any other option for this call scenario?


Which audio codecs are are negotiated in combination with DTMF inband using H323?

Message 4 of 4