If you negotiate for dtmf events, you cannot also expect to receive in band 
tones. Here's the wording from the RFC 4733:

If the sender receives an "events" parameter from the
   receiver, it MUST restrict the set of events it sends to those listed
   in the received "events" parameter.

They go on to give an example in the RFC if  you need more information:

https://tools.ietf.org/html/rfc4733


-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of Anh Cao
Sent: Sunday, October 23, 2016 9:14 PM
To: 'My Gmail' <[email protected]>; 'Kapila' <[email protected]>
Cc: [email protected]
Subject: Re: [Sip-implementors] DTMF digits dupplicate issue

Hi,

There is any standard/RFC for this?
Because my system only accept telephone-event packet and drop all in-band DTMF 
when I use SDP as below and I'm not sure it is correct.

Thanks,
Anh

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of My Gmail
Sent: Saturday, October 22, 2016 11:23 AM
To: Kapila <[email protected]>
Cc: [email protected]
Subject: Re: [Sip-implementors] DTMF digits dupplicate issue

Yes, its fine. The message mention indicates that both party support both 
codecs. Pcmu can  be used for both audio and dtmf and 101 only for dtmf. 

Thanks and Regards
Dheeraj Kumar 

Sent from iPhone

> On 22-Oct-2016, at 9:02 AM, Kapila <[email protected]> wrote:
> 
> Hi all,
> 
> Is it allowed to transmit dtmf in inband audio as well as in dynamic 
> payload type ?
> 
> in a recent deployment, we've noticed that Vendor X device sends the 
> dtmf in such way.
> The call scenario is a simple call that SDPs offers are,
> 
> UAC: Media Attribute (a): rtpmap:0 PCMU/8000,  Media Attribute (a):
> rtpmap:101 telephone-event/8000
> 
> 
> UAS: Media Attribute (a): rtpmap:0 PCMU/8000,  Media Attribute (a):
> rtpmap:101 telephone-event/8000
> 
> 
> Thanks
> Kapila
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> [email protected]
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