Bandwidth Requirements - Cisco 521SG - Unified IP Phone VoIP Administration Manual

Getting Started
Ensuring Voice Quality
Cisco Small Business SPA300 Series, SPA500 Series, and WIP310 IP Phone Administration Guide
Codec Complexity and Description
G.729 and G.729A low-medium complexity. G.729 medium
G.729A complexity.
G.729A requires about half the processing power
of G.729. The G.729 and G.729A bit streams are
compatible and interoperable, but not identical.
G.723. 1 High complexity. Cisco SPA IP phones support
the use of ITU G.723. 1 audio codec at 6.4 kbps.
Up to two channels of G.723. 1 can be used
simultaneously. For example, Line 1 and Line 2
can use G.723. 1 simultaneously, or Line 1 or
Line 2 can initiate a three-way conference with
both call legs using G.723. 1 .
G.723. 1 is not supported on the Cisco SPA525G
or Cisco SPA525G2 or Cisco WIP310 phones.
G.722 Only one G.722 call at a time is allowed. If a
conference call is placed, a SIP re-invite message
is sent to switch the calls to narrowband audio.
Not supported on the Cisco WIP310.

Bandwidth Requirements

Depending on how you have your IP phones configured, each call requires 55 to
110 kbps of the bandwidth in each direction. For example, using G.729 with an
average business-grade broadband Internet connection supporting 1.5 Mbps
downstream and 384 kbps upstream, a total of seven (7) simultaneous
conversations can be reliably supported with adequate bandwidth available for
file downloads.
We recommend using Cisco SPA IP phones with QoS-capable networking
equipment that can prioritize the VoIP traffic. A QoS-enabled device prioritizes the
packets going upstream to the ISP.
1
MOS
4
3.8
4.3
(approx)
31