Cisco SPA501G Administration Guide - Page 311

Cisco SPA IP Phone Field Reference Ext Tab A A codec resource is considered allocated if it has been included in the SDP codec list of an active call, even though it eventually might not be chosen for the connection. 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 G729a resource is already allocated (and since only one G.729a resource is allowed per phone), no other low-bit-rate codec can be allocated for subsequent calls. The only choices are G711a and G711u. Since two G.723.1/G.726 resources are available per IP phone, you should disable the use of G.729a to guarantee support for two simultaneous G.723/G.726 codecs. Dial Plan Script The default dial plan script for each line is as follows: (*xx|[3469]11|0|00|[2-9]xxxxxx|1xxx[29]xxxxxx|xxxxxxxxxxxx.). Cisco Small Business SPA300 Series, SPA500 Series, and WIP310 IP Phone Administration Guide 310