ZyXEL Communications Prestige 2002 - Manual (Page 55)

P-2002 Series User’s Guide
Chapter 5 Introduction to VoIP 55
5.6.1 G.711
G.711 is a Pulse Code Modulation (PCM) waveform codec. G.711 provides very good sound
quality but requires 64kbps of bandwidth.
5.6.2 G.729
G.729 is an Analysis-by-Synthesis (AbS) hybrid waveform codec that uses a filter based on
information about how the human vocal tract produces sounds. G.729 provides good sound
quality and reduces the required bandwidth to 8kbps.
5.7 PSTN Call Setup Signaling
Dual-Tone MultiFrequency (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
5.8 MWI (Message Waiting Indication)
Enable Message Waiting Indication (MWI) enables your phone to give you a message–waiting
(beeping) dial tone when you have a voice message(s). Your voice service provider must have
a messaging system that sends message waiting status SIP packets as defined in RFC 3842.
1. The Prestige does not support pulse dialing at the time of writing.