Chapter 17 VoIP
LTE-5121 User’s Guide
182
3
Client device A then sends the call invitation to client device C.
Figure 120
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 3550 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 76
SIP Call Progression
A
B
1. INVITE
2. Ringing
3. OK
4. ACK
5. Dialogue (voice traffic)
6. BYE
7. OK
1
2
3
A
B
C
Summary of Contents for LTE5121
Page 4: ...Contents Overview LTE 5121 User s Guide 4...
Page 12: ...Table of Contents LTE 5121 User s Guide 12...
Page 13: ...13 PART I User s Guide...
Page 14: ...14...
Page 22: ...Chapter 1 Introduction LTE 5121 User s Guide 22...
Page 28: ...28...
Page 42: ...Chapter 4 Broadband LTE 5121 User s Guide 42...
Page 70: ...Chapter 5 Wireless LTE 5121 User s Guide 70...
Page 98: ...Chapter 7 Static Route LTE 5121 User s Guide 98...
Page 102: ...Chapter 8 DNS Route LTE 5121 User s Guide 102...
Page 114: ...Chapter 9 Quality of Service QoS LTE 5121 User s Guide 114...
Page 138: ...Chapter 14 Parental Control LTE 5121 User s Guide 138...
Page 148: ...Chapter 15 Certificates LTE 5121 User s Guide 148...
Page 151: ...Chapter 16 VPN LTE 5121 User s Guide 151 Figure 104 IPSec VPN Add...
Page 162: ...Chapter 16 VPN LTE 5121 User s Guide 162...
Page 198: ...Chapter 19 User Account LTE 5121 User s Guide 198...
Page 214: ...Chapter 26 Backup Restore LTE 5121 User s Guide 214...
Page 224: ...Chapter 28 Troubleshooting LTE 5121 User s Guide 224...
Page 234: ...Index LTE 5121 User s Guide 234...