ZyXEL Communications P-2302R Series User Manual
P-2302R Series User’s Guide
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Chapter 7 Introduction to VoIP
7.9.1 Pulse Code Modulation
Pulse Code Modulation (PCM) measures analog signal amplitudes at regular time intervals
and converts them into bits.
and converts them into bits.
7.9.2 G.711
G.711 is a Pulse Code Modulation (PCM) waveform codec. G.711 provides very good sound
quality but requires 64kbps of bandwidth.
quality but requires 64kbps of bandwidth.
7.9.3 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.
information about how the human vocal tract produces sounds. G.729 provides good sound
quality and reduces the required bandwidth to 8kbps.
7.10 PSTN Call Setup Signaling
PSTNs (Public Switched Telephone Network)s use DTMF or pulse dialing to set up telephone
calls.
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.
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.
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7.11 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.
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 supports DTMF at the time of writing.