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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
Converged Voice Gateway
The Cisco Voice Gateway 200 (VG200) allows you to connect the standard POTS phones (connected
directly to the gateway or anywhere on the PSTN) with Cisco IP or any H.323-compliant telephony
devices. When used with Cisco CallManager, the VG200 functions as a Media Gateway Control Protocol
(MGCP) gateway. The Cisco VG200 provides a 10/100BASE-T Ethernet port for connection to the data
network. The following telephony connections are also available:
•
One to four Foreign Exchange Office (FXO) ports for connecting to a central office or PBX
•
One to four FXS ports for connecting to POTS telephony devices
Table 55-2
8-Port T1/E1 PSTN Interface Module Features
Digital Signal Processing Per T1/E1 Port
G.711 to G.723 and G.729a transcoding (maximum of 8 x 32 channels of transcoding)
Conference bridging, meet-me, and ad-hoc conference modes (maximum of 8 x 16 channels of
conferencing)
Comfort noise generation
Fax pass-through
Silence suppression, voice activity detection
Line echo cancellation
Common channel signaling
For T1: 23 DS0 channels for voice traffic; 24th channel is used for signaling
For E1: 29 DS0 channels for voice traffic; 16th channel is reserved for signaling
Any channel can be configured for common channel signaling
ISDN Primary Rate Interface signaling: Each interface supports 23 channels for T1 and 30 channels
for E1. The default mode is for the 24th T1 channel or 16th E1 channel to be reserved for signaling.
Both network side and user side operation modes are supported.
T1 binary 8-zero substitution/alternate mark inversion (B8ZS/AMI) line coding, u-law or a-law
coding
E1 HDB3 line coding
T1 line bit rate: 1.544 Mbps
E1 line bit rate: 2.048 Mbps
T1 line code: AMI, B8ZS
E1 line code: HDB3
Framing format: D4 superframe and extended superframe
Link Management
FDL
1
is a link management protocol that is used to help diagnose problems and gather statistics on
T1 lines
1.
FDL = Facilities Data Link