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difference between dtmf-relay sip-notify and dtmf-relay rtp-nte

Rachna Sharma
Level 1
Level 1

Fellows,

Can anyone please explain the difference between dtmf-relay sip-nitofy and dtmf-relay rtp-nte.

When and why to use this.

Regards,

Rachna

3 Replies 3

Marwan ALshawi
VIP Alumni
VIP Alumni

DTMF tones are created when a digit is dialed on a telephone. By default, the gateway sends these tones within the voice RTP stream. When voice is sent uncompressed, these tones arrive in their original state. However, when voice is compressed, such as with the G.729 codec, the tones might be distorted, or part of the signal might be lost. DTMF Relay addresses this by separating these tones from the rest of the voice and then sending them in a different way

example when you call and IVR or caontact center you need to press 1 to go to sales for example and this button is the DTMF

RTP-NTE Uses a method specified in RFC 2833 to send DTMF tones within the RTP stream, in a special Named Telephony Event (NTE) packet. The use of this method and the payload type value is negotiated on a call-by-call basis.

H.245 Alphanumeric Is specified by the ITU-T H.245 standard. Tones are sent over the H.245 signaling channel, rather than in-band with voice traffic. H.245 transmits DMTF tones to the receiving gateway as the ASCII character it represents (1, 2, 3, and so on). It does not send tone-length information. Each tone is assumed to last 500 milliseconds (ms). All H.323 gateways must support this type of

DTMF RelayH.245 Alphanumeric Is specified by the ITU-T H.245 standard. Tones are sent over the H.245 signaling channel, rather than in-band with voice traffic. H.245 transmits DMTF tones to the receiving gateway as the ASCII character it represents (1, 2, 3, and so on). It does not send tone-length information. Each tone is assumed to last 500 milliseconds (ms). All H.323 gateways must support this type of DTMF Relay

SIP has its own DTMF types too

hope this help

if helpful Rate

Hi

dtmf-relay rtp-nte :

          DTMF tones are transported in the RTP voice packet itself using the NTE method for encoding and decoding on respective endpoints

dtmf-relay sip-notify

          When the DTMF is recognized, the Sip Gateway uses Sip Notify which is a signalling message.

Regards,

Senthilkumar

SemoTech
Level 1
Level 1

Experiencing issues on a UC520 with DTMF myself, as button presses are no longer registering, after switching to T-Mobile Internet (via Cellular) but while using the same SIP provider (Level 3). 

I checked my UC520 configuration and it seems ALL my "dial-peer voice XXXX voip" profiles are configured using "dtmf-relay rtp-nte".

2023-06-21_14-34-53.jpg

Never had any DTMF issues with my SIP provider of 5 years (Level 3), until I switched from Cable Internet to T-Mobile Internet (via cellular), and while everything else works fine with T-Mobile, just the Touch-Tone DTMF feature stopped working altogether.  I initially assumed this may be due to the higher latency (50-80ms) of the cellular connection, but I read that up to 150ms latency should still be OK, so this may be something else.

Should I replace all instances of "dtmf-relay rtp-nte" with "dtmf-relay sip-notify", for all my dial-peer voice profiles, or is the DTMF failure related to how T-Mobile cellular Internet works and therefore a different fix is needed?

Any ideas on how to get DTMF working again with T-Mobile Internet?

Thanks!