Cisco SPA1001 Administration Guide - Page 42

Establishing Connectivity Chapter 2 Getting Started Table 1-23 WRTP54G Back Panel Port Ethernet 1-3 Power Function Connect to local IP devices, such as PCs, using an Ethernet cable. Connect to the power supply. Establishing Connectivity This section describes how to connect the Linksys ATA hardware. It includes the following topics: • Bandwidth Requirements, page 2-14 • Making the Physical Connections, page 2-15 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. Table 1-24 illustrates the bandwidth budget using different codecs. Table 1-24 Ethernet Bandwidth Budget for Off-Net VoIP Calling Codec Approximate bandwidth budget for each side of conversation G.711 110 kbps G.726-40 87 kbps G.726-32 79 kbps G.726-24 71 kbps G.726-16 63 kbps G.729 55 kbps 2 calls 220 kbps 174 kbps 158 kbps 142 kbps 126 kbps 110 kbps 4 calls 440 kbps 348 kbps 316 kbps 284 kbps 252 kbps 220 kbps 6 calls 8 calls 660 kbps 880 kbps 522 kbps 696 kbps 474 kbps 632 kbps 426 kbps 568 kbps 378 kbps 504 kbps 330 kbps 440 kbps This table is based on the following assumptions: • Bandwidth Calculated with No Silence Suppression • 20 milliseconds 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: 2-14 Linksys ATA Administrator Guide Document Version 3.1