1. Call signaling/Media control
Figure 8-1 Comparing PSTN and VoIP voice call setup
Circuit-switched Network
Media Gateway
IP Network
Call signaling/Media control
Call signaling
Media control
Media exchange
Media exchange

2. Figure 8-2 Relationship Between Signaling and Media Flow
IP Phone – Calling party IP
Media Gateway
IP Phone – Called party
Call setup Signaling
Media Flow
8001
8002

3. Figure 8-3 Components of a Multimedia Communication Service
H.323 Terminal
H MCU
H.323 Gatekeeper
H.323 Gateway
IP Network
PSTN
ISDN

4. Figure 8-4 Gatekeeper Gatekeeper Media Gateway IP IP WAN Router
IP Phones IP
Media Gateway
Router
IP WAN
Gatekeeper
MCU

5. Figure 8-5 H.323 Zones IP Phones IP Media Gateway Router IP WAN
Gatekeeper
MCU

6. Figure 8-6 Interdomain routing
AS 300
AS 200
AS 100
BGP protocol running here connecting the three AS (Autonomous Systems) together

7. Figure 8-7 Signaling separate from VoIP conversation
Real time Transport Protocol VoIP Conversation
UDP
Call setup signaling
1. Off hook
2. Send Dial tone
3. Dial number
6 Receive IP
4. is phone on hook? Yes
5 .Give caller ip address
7. set up UDP port
8. Ring signal
Called party
Calling party
Signaling uses TCP/IP
Conversation uses UDP
Media Gateway

8. Chapter 8 Figures
[FIG] Figure 8-1 Comparing PSTN and VoIP voice call setup
[FIG] Figure 8-2 Relationship between signaling and media flow
[FIG] Figure 8-3 Components of a multimedia communication service
[FIG] Figure 8-4 Gatekeeper
[FIG] Figure 8-5 H.323 Zones
[FIG] Figure 8-6 Interdomain routing
[FIG] Figure 8-7 Signaling separate from VoIP converstion