DTMF & Negotiation

[sherif.elella]

dear community,

i am routing a call as such:

phone --> CUCM X--> SIP Trunk A --> CUCME --> SIP Trunk A --> CUCM X --> SIP Trunk B --> non-Cisco SIP Server

when i initiate a call, it shows me under "show sip-ua calls" two RTP Streams that dont make sense for some reason .. i am getting one way audio, but i noticed something odd about DTMF

first stream is 

Negotiated Dtmf-relay    : rtp-nte

second stream is 

 Negotiated Dtmf-relay    : inband-voice

when i read up on it, i understood that inband-voice means RFC2833, but the same time so does rtp-nte ... i am confused at this point and the packets show 

a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15

anyone can explain whats going on? or what does inband-voice dtmf actually mean?

[Ayodeji Okanlawon]

Sherif,

The names are sometimes confusing but inband-voice is not the same as rfc2833.

When you're not doing DTMF at all, many people still call this in-band. This is when the tones physically exist in the audio stream.  Inband-voice is what the gateway defaults to when it cant negotiate any dtmf. So when you see this, most means you are not going to get any dtmf on the call