Analog Devices CRA-200 - Manual (Page 7)

_____________________________ CRA-200 Quick Installation Guide
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Page: 7 of 7
For example, in networks with 128k DSL, a total of no more than
7 simultaneous calls are recommended with a G.723 90ms codec
configuration and VPN enabled.
NOTE: The DSL speeds in the table above refer to the Minimum
Upload and Download transfer rate. Please be aware that
your internet bandwidth may fluctuate depending on
your provider’s availability. Results may vary depending
on fluctuations of bandwidth availability. A decrease in
available bandwidth will directly relate to a decrease
in total number of allowable calls and possibly call
quality depending on bandwidth over­utilization.
IMPORTANT: These figures assume that the bandwidth is
dedicated solely for these voice calls and that
the broadband service provider has committed
this bandwidth to the installation. The use of
other Internet services may adversely affect the
amount of allowable simultaneous calls along
with call quality.
.
Codec Latency Configuration: This setting on the SIP
Configuration page determines the voice samples per packet.
The number of voice samples per packet is another factor in
determining the bandwidth utilized and delay of a VoIP call. The
CODEC defines the size of the sample (G.711 and G.729 have a
sample size of 10ms and G.723 has a sample size of 30ms), but
the total number of samples placed in a packet affects how many
packets are sent per second. When you increase the voice
payload size, the bandwidth utilized is reduced and the overall
delay increases. Increasing these settings (for example ‐ from
30ms to 90ms for G.723) can reduce bandwidth utilization, but
in turn it may affect voice quality depending on the quality and
stability of your connection. For example, if you drop one packet
due to connectivity issues, a setting of G.723/30ms will lose one
voice sample where a setting of G.723/90ms will lose 3 voice
samples.