Cisco SPA301 Administration Manual page 151

Configuring Security, Quality, and Network Features
Configuring Voice Codecs
Cisco Small Business SPA300 Series, SPA500 Series, and WIP310 IP Phone Administration Guide
Negotiation of the optimal voice codec sometimes depends on the ability of the
Cisco SPA IP phones to match a codec name with the far-end device or gateway
codec name. Cisco SPA IP phones allow the network administrator to individually
name the various codecs that are supported such that the correct codec
successfully negotiates with the far-end equipment.
Note that Cisco SPA IP phones support voice codec priority. You can select up to
three preferred codecs. The administrator can select the low-bit-rate codec used
for each line. G.711a and G.711u are always enabled.
To configure the voice codecs on each extension, navigate to Admin Login >
advanced > Voice > Ext_n. Under Audio Configuration, configure the following
parameters:
Parameter
Preferred Codec
Use Pref Codec
Only
Description
Preferred codec for all calls. (The actual codec used in a
call still depends on the outcome of the codec negotiation
protocol.) Select one of the following:
• G711u (all models)
• G711a (all models)
• G726-16 (not supported on Cisco WIP310,
Cisco SPA525G or Cisco SPA525G2)
• G726-24 (not supported on Cisco WIP310,
Cisco SPA525G or Cisco SPA525G2)
• G726-32 (all models)
• G726-40 (not supported on Cisco WIP310,
Cisco SPA525G or Cisco SPA525G2)
• G729a (all models)
• G723 (not supported on Cisco WIP310,
Cisco SPA525G or Cisco SPA525G2)
• G722 (not supported on Cisco WIP310)
Defaults to G711u.
To use only the preferred codecs for all calls, select yes.
(The call fails if the far end does not support these
codecs.) Otherwise, select no. Defaults to no.
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