ZyXEL Communications P-2701RL User Manual page 17

Table 2 SIP Setting (continued)
LABEL
DTMF Relay
RFC2833
Payload Type
SIP INFO
Duration (ms)
Call Waiting
DNS SRV
Figure 6 Advanced SIP Settings (part 2)
P-27XX Series User's Guide
DESCRIPTION
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.
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.
Specify DTMF tone play duration in milliseconds.
Select this to enable the call waiting feature, if supported by your phone
or SIP service provider.
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.
Chapter 3 Phone Use and Configuration
17