Configuring Security, Quality, and Network Features
Configuring Voice Codecs
Cisco Small Business SPA300 Series, SPA500 Series, and WIP310 IP Phone Administration Guide 137
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To configure the voice codecs on each extension:
STEP 1 Log in to the configuration utility. 
STEP  2 Click Admin Login and advanced.
STEP  3 Click the Ext <number> tab for the extension you want to configure.
STEP  4 Under Audio Configuration, configure the following parameters:
Parameter  Description
Preferred Codec  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 WIP310, SPA525G/525G2)
• G726-24 (not supported on WIP310, SPA525G/525G2)
• G726-32
• G726-40 (not supported on WIP310, SPA525G/525G2)
• G729a
• G723 (not supported on WIP310, SPA525G/525G2)
• G722 (not supported on WIP310)
See “Supported Codecs” section on page 132.
Defaults to G711u.
Use Pref Codec 
Only 
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.
Second Preferred 
Codec
If the first codec fails, this codec is tried.
Defaults to unspecified.
NOTE Not applicable to the WIP310.