Chapter 3 Phone Use and Configuration

Table 2 SIP Setting (continued)

LABEL

DESCRIPTION

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

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

Payload Type

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

Specify DTMF tone play duration in milliseconds.

Duration (ms)

 

 

 

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.

 

 

Figure 6 Advanced SIP Settings (part 2)

20

 

P-27XX Series User’s Guide