Configuring Cisco 79xx phones with Asterisk
By default most Cisco VoIP phones come configured for Call Manager, which uses the ‘Skinny’ protocol – SCCP.
Asterisk has 2 implementations for this channel (required for the 7910/20):
Skinny implements a very basic set of telephone functions and ships with asterisk.
SCCP has implemented more of the SCCP protocol, so some class 5 features (hold, transfer, forward, etc) should work.
However, the 7905/7912 and 7940/60 can be reconfigured to use SIP (recommended for use with Asterisk): http://www.cisco.com/en/US/products/hw/phones/ps379/products_tech_note09186a0080094584.shtml
The 7905 doesn’t have Speakerphone (only a speaker for call monitoring or on-hook dialing), its SIP image has by far the best user interface of all cisco SIP phones, plus it’s nicely compact, and the display even has a higher resolution than that of the 7960. The 7912 is the same as the 7905, but with a built-in ethernet switch.
The 7912/05 phones use a different configuration file format and syntax; for more information about configuring these phones please refer to ((Cisco 7905/7912 IP Phones)).
With the right Cable, 79xx series phones can use standard POE injectors. They also work out of the box with Aironet power injectors. (N.B., the wrong cable may damage your phone!)
let me know if it helps.