Configuring DTMF transmission
In conversation, DTMF digits can be transmitted transparently between originating and terminating gateways in inband or out-of-band mode:
Inband transmission—DTMF dialing tones are transmitted to the peer end as normal voice packets.
Out-of-band transmission—Corresponding information is extracted from DTMF digits and is then encapsulated in H.245, H.225, SIP, or RTP packets (RFC 2883) for transmission. The transmission of DTMF digits in RTP packets is also called as NTE mode.
Configuration guidelines
When you configure DTMF transmission, follow these guidelines:
Both H.323 and SIP support NTE.
Because the implementations of different vendors can differ, Hewlett Packard Enterprise recommends that you configure command outband nte and the same payload type value on both the originating and terminating sides. Otherwise, NTE negotiation might fail and thus the user cannot receive DTMF tones.
It is forbidden to set the NTE payload type field to 98, which has already been used to identify nonstandard T.38 fax packets.
When the device is connected with other manufacturers' routers for communication, you cannot set the payload type field to any forbidden by these routers. Otherwise, an NTE negotiation failure might occur.
Configuration procedure
To configure out-of-band DTMF transmission:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter voice view. | voice-setup | N/A |
3. Enter voice dial program view. | dial-program | N/A |
4. Create a POTS voice entity and enter POTS voice entity view. | entity entity-number pots | N/A |
5. Configure out-of-band DTMF transmission. | outband { h225 | h245 | nte | sip } | Optional. By default, inband transmission is adopted. |
6. Configure the value of the payload type used by NTE. | rtp payload-type nte value | Optional. The default is 101. |