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dtmf-relay
Voice over IP for the Cisco AS5800 25
dtmf-relay
To specify how an H.323 gateway relays dual tone multifrequency (DTMF) tones between telephony
interfaces and an IP network, use the dtmf-relay dial-peer configuration command. To remove all
signaling options and transmit the DTMF tones as part of the audio stream, use the no form of this
command.
dtmf-relay [cisco-rtp] [h245-alphanumeric] [h245-signal]
no dtmf-relay
Syntax Description
Defaults
No default behavior or values.
Command Modes
Dial-peer configuration
Command History
Usage Guidelines
DTMF is the tone generated when you press a digit on a touch-tone phone. This tone is compressed
at one end of a call; when the tone is decompressed at the other end, it can become distorted,
depending on the codec used. The DTMF relay feature transports DTMF tones generated after call
establishment out of band using a standard H.323 out-of-band method and a proprietary RTP-based
mechanism.
The gateway sends DTMF tones in the format you specify only if the remote device supports it. If
the remote device supports multiple formats, the gateway chooses the format based on the following
priority:
• cisco-rtp (highest priority)
• none, meaning that the DTMF is sent in-band
cisco-rtp (Optional) Forwards DTMF tones by using RTP protocol with a
Cisco proprietary payload type.
h245-alphanumeric (Optional) Forwards DTMF tones by using the H.245
“alphanumeric” User Input Indication method. Supports tones
0-9, *, #, and A-D.
h245-signal (Optional) Forwards DTMF tones by using the H.245 “signal”
User Input Indication method. Supports tones 0-9, *, #, and
A-D.
Release Modification
12.0(7)T This command was introduced.