55-5
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 55 Configuring a VoIP Network
Understanding How a VoIP Network Works
Cisco CallManager
Cisco CallManager is an open and industry-standard call processing system; its software runs on a
Windows NT server and sets up and tears down the calls between the phones, integrating traditional PBX
functionality with the corporate IP network. Cisco CallManager manages the components of the IP PBX
system, the phones, the access gateways, and the resources for such features as call conferencing and
media mixing. Each Cisco CallManager manages the devices within its
zone
and exchanges information
with the Cisco CallManager in charge of another zone to make the calls possible across multiple zones.
Cisco CallManager can work with the existing PBX systems to route a call over the Public Switched
Telephone Network (PSTN).
Note
For information on configuring Cisco CallManager to work with the IP devices that are described in this
chapter, refer to the
Cisco CallManager Administration Guide,
the
Configuration Notes for Cisco
CallManager,
and the
Cisco CallManager Remote Serviceability Users Guide
publications
.
Access Gateways
The access gateways allow the IP PBX system to talk to the existing PSTN or PBX systems. The access
gateways consist of analog station gateways, analog trunk gateways, digital trunk gateways, and a
converged
voice gateway.
These sections describe the gateways:
•
Analog Station Gateway, page 55-5
•
Analog Trunk Gateway, page 55-6
•
Digital Trunk Gateway, page 55-6
•
Converged Voice Gateway, page 55-7
Analog Station Gateway
The Catalyst 6500 series 24-port Foreign Exchange Station (FXS) analog interface module allows the
plain old telephone service (POTS) phones and fax machines to connect to the IP PBX network. The
analog station gateway behaves like the PSTN side for the POTS equipment. It requires an IP address,
is registered with Cisco CallManager in its domain, and is managed by Cisco CallManager.
To configure the analog station interfaces, see the
“Configuring VoIP on a Switch” section on
page 55-10
. The module features are listed in
Table 55-1
.
Table 55-1
24-Port FXS Analog Interface Module Features
Digital Signal Processing Per Port
G.711 and G.729 voice encoding
Silence suppression; voice activity detection
Comfort noise generation
Ringer, software programmable frequency and cadence, based on country
DTMF
1
detection
Signaling, loop start