Cisco Systems 3522 BRI, 3527 PRI manual About PRI Gateway Call Handling Capacity

Chapter 1 Functionality

About Cisco Unified Videoconferencing 3500 Gateway Functionality

About PRI Gateway Call Handling Capacity

Table 1-3lists the maximum call handling capacity of the PRI gateway for different types of calls.

Table 1-3	PRI Gateway Call Handling Capacity
Call Type		Maximum Number of	Maximum Number of
		Calls Using 1 x E1 PRI	Calls Using 1 X T1 PRI
		Line	Line
voice (64 Kbps)		30	23
2B video (128 Kbps)		15	11
6B video (384 Kbps)		5	3
12B video (768 Kbps)		2	1

Note Enabling ISDN-to-IP DTMF detection in the PRI gateway for video calls reduces the number of supported calls by half.

About BRI Gateway Call handling Capacity

Table 1-4lists the maximum call handling capacity of the BRI gateway for four BRI lines, eight voice-only calls, or eight video calls, or any combination of the two.

Table 1-4	BRI Gateway Call Handling Capacity
Number of Calls		Capacity
1		384	Kbps+ or 412 Kbps
2		256	Kbps
4		128	Kbps
8		64 Kbps

About Gateway Call Bandwidth Overhead

According to the H.320 standard, the available bandwidth allocated to a call at any given bit rate will always be slightly less than the stated maximum for the following reasons:

•All stated maximum call bandwidths include provision for control, audio, video, and data traffic.

•Video traffic on the ISDN side contains additional bits for error correction purposes which also consume bandwidth. Video traffic on the IP side does not include this additional load.

•Opening an audio channel further reduces the bandwidth available to the video traffic.

For example, a call at 384 Kbps actually has only 363 Kbps available to it. Control and error correction account for the remaining 21 Kbps.

	Installation and Upgrade Guide for Cisco Unified Videoconferencing 3522 BRI Gateway and 3527 PRI Gateway Release 5.5
OL-14910-01		1-11