Cisco WS C4224V 8FXS - 200Mbps Ethernet Switch Software Configuration Manual page 30

Solution
Figure 1-1 Centralized Call Processing Solution
A
C
B
V
Catalyst 4224 Access Gateway Switch Software Configuration Guide
1-4
VIC/WIC ISDN BU MFT-T1
Single T-1 access to
each branch office
IP WAN
PSTN
In the diagram, a Cisco CallManager cluster at a central site uses Simple Client
Control Protocol (SCCP) to control IP phones at two branch offices. In the branch
VoIP network, a Catalyst 4224 acts as an H.323 gateway, interconnecting the
analog devices, the PSTN, and IP WAN. This system uses ISDN Basic Rate
Interface (BRI) as a lifeline to the PSTN.
If the WAN link (or the Cisco CallManager cluster) becomes unavailable,
Survivable Remote Site Telephony (SRST) allows the Catalyst 4224 to keep the
IP phones on the branch networks running. Under these circumstances, the
Catalyst 4224 functions as an H.323 gateway, thereby ensuring uninterrupted
connectivity to the PSTN.
Catalyst 4224
12 Channels voice/
12 Channels data
Chapter 1 Product Overview
IP
IP
IP
IP
OL-2031-02