Establishing Connectivity; Bandwidth Requirements - Linksys SPA1001 Administrator User Manual

Establishing Connectivity

Table 1-23 WRTP54G Back Panel
Port
Ethernet 1-3
Power
Establishing Connectivity
This section describes how to connect the Linksys ATA hardware. It includes the following topics:
•
•

Bandwidth Requirements

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 ATA 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 1-24 Ethernet Bandwidth Budget for Off-Net VoIP Calling
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:
•
•
For more information about bandwidth calculation, refer to the following websites:
Linksys ATA Administrator Guide
2-14
Function
Connect to local IP devices, such as PCs, using an Ethernet cable.
Connect to the power supply.
Bandwidth Requirements, page 2-14
Making the Physical Connections, page 2-15
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 milliseconds of payload per RTP packet
The use of silence suppression can reduce the average bandwidth budget by 30% or more.
Note
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 1-24
8 calls
880 kbps
696 kbps
632 kbps
568 kbps
504 kbps
440 kbps
Document Version 3.1