Chapter 21 Voice
185
3
Client device
A
then sends the call invitation to client device
C
.
Figure 115
SIP Redirect Server
SIP Register Server
A SIP register server maintains a database of SIP identity-to-IP address (or domain name) mapping.
The register server checks your user name and password when you register.
RTP
When you make a VoIP call using SIP, the RTP (Real time Transport Protocol) is used to handle voice
data transfer. See RFC 1889 for details on RTP.
Pulse Code Modulation
Pulse Code Modulation (PCM) measures analog signal amplitudes at regular time intervals and
converts them into bits.
SIP Call Progression
The following figure displays the basic steps in the setup and tear down of a SIP call. A calls B.
Table 104
SIP Call Progression
A
B
1. INVITE
2. Ringing
Summary of Contents for Movistar GPT-2541GNAC
Page 47: ...Chapter 4 LAN 47 Figure 25 LAN Setup...
Page 99: ...Chapter 11 DNS 99 Figure 62 DNS Server...
Page 144: ...Chapter 20 Wireless 144 Figure 92 Wireless Security...
Page 166: ...Chapter 21 Voice 166...
Page 196: ...Chapter 21 Voice 196...