ZyXEL Communications MAX-200M1 Series, Руководство пользователя

Страница: 111 / 258

ZyXEL MAX-200M1 Series User’s Guide
Chapter 10 SIP 111
• G.729 is an Analysis-by-Synthesis (AbS) hybrid waveform codec. It uses a filter based on
information about how the human vocal tract produces sounds. The codec analyzes the
incoming voice signal and attempts to synthesize it using its list of voice elements. It tests
the synthesized signal against the original and, if it is acceptable, transmits details of the
voice elements it used to make the synthesis. Because the codec at the receiving end has
the same list, it can exactly recreate the synthesized audio signal.
G.729 provides good sound quality and reduces the required bandwidth to 8kbps.
10.1.9 PSTN Call Setup Signaling
PSTNs (Public Switched Telephone Networks) use DTMF or pulse dialing to set up telephone
calls.
Dual-Tone Multi-Frequency (DTMF) signaling uses pairs of frequencies (one lower frequency
and one higher frequency) to set up calls. It is also known as Touch Tone®. Each of the keys
on a DTMF telephone corresponds to a different pair of frequencies.
Pulse dialing sends a series of clicks to the local phone office in order to dial numbers.
1
10.1.10 MWI (Message Waiting Indication)
Enable Message Waiting Indication (MWI) enables your phone to give you a message–waiting
(beeping) dial tone when you have one or more voice messages. Your VoIP service provider
must have a messaging system that sends message-waiting-status SIP packets as defined in
RFC 3842.
10.1.11 Custom Tones (IVR)
IVR (Interactive Voice Response) is a feature that allows you to use your telephone to interact
with the ZyXEL Device. The ZyXEL Device allows you to record custom tones for the
Caller
Ringing Tone and On Hold Tone functions. The same recordings apply to both the caller
ringing and on hold tones.
1. The ZyXEL Device supports DTMF at the time of writing.
Table 32 Custom Tones Details
LABEL DESCRIPTION
Total Time for All Tones 128 seconds for all custom tones combined
Maximum Time per Individual
Tone
20 seconds
Total Number of Tones
Recordable
8
You can record up to eight different custom tones but the total time must
be 128 seconds or less.