Linksys SPA 900 Series Manuale Utente
2-10
Linksys IP Phone Administrator Guide
Firmware Version 5.1
Chapter 2 Getting Started
Establishing Connectivity
•
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.
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.
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.
This table is based on the following assumptions:
•
Bandwidth Calculated with No Silence Suppression
•
20 Millisecond of payload per RTP packet
Note
The use of silence suppression can reduce the average bandwidth budget by 30% or more.
For more information about bandwidth calculation, refer to the following websites:
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:
•
Linksys 900 Series phone
•
Ethernet cable
•
Power adapter (must be ordered separately for PoE units: SPA922, SPA942, and SPA962)
Table 2-1
Ethernet Bandwidth Budget for Off-Net VoIP Calling
Codec
Approximate bandwidth budget for
each side of conversation
each side of conversation
2 calls
4 calls
6 calls
8 calls
G.711
110 kbps
220 kbps
440 kbps
660 kbps
880 kbps
G.726-40
87 kbps
174 kbps
348 kbps
522 kbps
696 kbps
G.726-32
79 kbps
158 kbps
316 kbps
474 kbps
632 kbps
G.726-24
71 kbps
142 kbps
284 kbps
426 kbps
568 kbps
G.726-16
63 kbps
126 kbps
252 kbps
378 kbps
504 kbps
G.729
55 kbps
110 kbps
220 kbps
330 kbps
440 kbps