Cisco SPA IP Phone Field Reference
Ext Tab
Cisco Small Business SPA300 Series, SPA500 Series, and WIP310 IP Phone Administration Guide 307
B
Audio Configuration
A codec resource is considered as allocated if it has been included in the SDP
codec list of an active call, even though it eventually may not be the one chosen for
the connection. So, if the G.729a codec is enabled and included in the codec list,
that resource is tied up until the end of the call whether or not the call actually uses
G.729a. If the G.729a resource is already allocated and since only one G.729a
resource is allowed per device, no other low-bit-rate codec may be allocated for
subsequent calls; the only choices are G711a and G711u. On the other hand, two
G.723.1/G.726 resources are available per device.
Therefore it is important to disable the use of G.729a in order to guarantee the
support of two simultaneous uses of the G.723/G.726 codecs.
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, G711a, G722, G726-16, G726-24, G726-32,
G726-40, G729a, or G723.
NOTE Cisco SPA525G/525G2 choices are: G711u,
G711a, G726-32, G729a, and G722. G.723 not available
on SPA300 Series or SPA500 Series. G722 not
available on WIP310.
Defaults to G711u.
Use Pref Codec Only To use only the preferred codec for all calls, select yes.
(The call fails if the far end does not support this
codec.) Otherwise, select no.
Defaults to no.
Second Preferred Codec The second preferred codec when the preferred
codec cannot be used. If
Use Pref Codec Only i
s
enabled (set to yes), this parameter is not used.
Defaults to Unspecified.
Third Preferred Codec The third preferred codec when the preferred codec
and second preferred codec cannot be used. If
Use
Pref Codec Only i
s enabled (set to yes), this parameter
is not used.
Defaults to Unspecified.
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