User's Manual

Chapter 3 Phone Use and Configuration

P-27XX Series User’s Guide

Figure 6 Advanced SIP Settings (part 2)

DTMF Relay Dual-Tone Multi-Frequency (DTMF) relay detects DTMF signals and

sends them out-of-band (via SIP or RTP) to the remote party. DTMF

relay is used when a low-bitrate voice codec might distort DTMF signals

sent over the voice channel.

The available relay types are:

• RFC2833 - Relays DTMF tones in outband RTP packets.

• SIP INFO - Relays DTMF tones in outband SIP packets.

• PCM - Relays DTMF tones in the voice data stream. PCM provides

very good sound quality with certain codecs (such as G.711) but

requires 64 kbps of bandwidth. With other codecs (such as G.729),

sound distortion may occur.

RFC2833

Payload Type

This defines the DTMF tone type in decimal encoding, and which allows

gateways to recognize a DTMF tone that has been embedded in a voice

signal and then respond accordingly.

Enter a digit that corresponds directly to a payload event type, as

defined in the RFC-2833 standard.

SIP INFO

Duration (ms)

Specify DTMF tone play duration in milliseconds.

Call Waiting Select this to enable the call waiting feature, if supported by your phone

or SIP service provider.

DNS SRV Select Enable to have the ZyXEL Device query your ISP’s DNS server

for a list of any available SIP servers that it maintains. This is useful if

your static SIP server exeriences difficulties, making it hard for your IP

phone users to make SIP calls.

Table 2 SIP Setting (continued)

LABEL DESCRIPTION