Bandwidth Requirements1; Installing The Spa900 Series Ip Phone - Linksys SPA 900 Series Administration Manual

Establishing Connectivity
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Bandwidth Requirements1

Depending on how you have your IP phones configured, each call requires 55 to 110 kbps in each
direction. Therefore, using G.729 as the voice codec setting, and 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.
Linksys recommends using the Linksys IP phone with QoS-capable networking equipment that can
prioritize the VoIP application traffic. QoS features are available on many Linksys data networking
switches and routers. A QoS-enabled router prioritizes the packets going upstream to the ISP.
illustrates the bandwidth budget using different codecs.
Table 2-1
Codec
G.711
G.726-40
G.726-32
G.726-24
G.726-16
G.729
This table is based on the following assumptions:
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For more information about bandwidth calculation, refer to the following websites:
http://www.erlang.com/calculator/lipb/
http://www.packetizer.com/voip/diagnostics/bandcalc.html

Installing the SPA900 Series IP Phone

This section describes how to install and verify operation of SPA900 Series IP phones.
Check to make sure that you have the following package contents:
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Linksys IP Phone Administrator Guide
2-10
Installing the SPA900 Series IP Phone, page 2-10
Ethernet Bandwidth Budget for Off-Net VoIP Calling
Approximate bandwidth budget for
each side of conversation
110 kbps
87 kbps
79 kbps
71 kbps
63 kbps
55 kbps
Bandwidth Calculated with No Silence Suppression
20 Millisecond of payload per RTP packet
The use of silence suppression can reduce the average bandwidth budget by 30% or more.
Note
Linksys 900 Series phone
Ethernet cable
Power adapter (must be ordered separately for PoE units: SPA922, SPA942, and SPA962)
Chapter 2
2 calls 4 calls 6 calls
220 kbps 440 kbps 660 kbps
174 kbps 348 kbps 522 kbps
158 kbps 316 kbps 474 kbps
142 kbps 284 kbps 426 kbps
126 kbps 252 kbps 378 kbps
110 kbps 220 kbps 330 kbps
Getting Started
Table 2-1
8 calls
880 kbps
696 kbps
632 kbps
568 kbps
504 kbps
440 kbps
Firmware Version 5.1