Enable Dtmf Relay; Enable Echo Canceller - Patton electronics SmartNode Series Software Configuration Manual

30 • VoIP profile configuration

Enable DTMF relay

Dual tone multi-frequency (DTMF) tones are usually transported accurately in band when using high-bit-rate
voice codecs such as G.711. Low-bit-rate codecs such as G.729 and G.723.1 are highly optimized for voice
patterns and tend to distort DTMF tones. The dtmf relay command solves the problem of DTMF distortion
by transporting DTMF tones out-of-band or separate from the encoded voice stream as illustrated in
Figure 74. H.323 signals the DTMF tones as H.245 User Input Indications (more precisely as Basic Strings) as
most H.323 gateways do.
This procedure describes how to enable DTMF relay
Mode: Profile VoIP
Step Command
1 node (pf-voip)[ name ]#dtmf-relay
node (pf-voip)[ name ]#exit
2
node (cfg)#context cs
3
4 node (ctx-cs)[switch]#interface isoip name
or
node (ctx-cs)[switch]#interface h323 name
node (if-type)[ if-name ]#no dtmf-relay
5
Example: Enabling DTMF relay
The following example shows how to enable DTMF relay for the VoIP profile and disable it for the ISoIP
interface.
SN>enable
SN#configure
SN(cfg)#profile voip ISoIPProfile
SN(pf-voip)[ISoIPPr~]#dtmf-relay
SN(pf-voip)[ISoIPPr~]#exit
SN(cfg)#context cs
SN(ctx-cs)[switch]#interface isoip IpBackbone
SN(if-isoip)[IpBackb~]#no dtmf-relay

Enable echo canceller

Echoes are reflections of the transmitted signal, which result from impedance mismatch in the hybrid (bi-direc-
tional 2-wire to 4-wire converting) device. Some voice devices unfortunately have an echo on their wire. Echo
cancellation provides near-end echo compensation for this device as illustrated in
380
Figure 74. DTMF Relay
Purpose

Enable DTMF relay

Optional:
Change to CS interface configuration mode to
overwrite the settings in the VoIP profile in a
specific CS interface
Disable DTMF relay on a specific interface
SmartWare Software Configuration Guide
figure 75.
VoIP profile configuration task list