Hi Hicham,
If you don't see it offered up as a valid phone choice via "Add new Phone" or in the Device Defaults you will need to upgrade to at least the Device Pak indicated below;
Before installing the firmware, use Table 1 below to verify that your Cisco Unified Communications Manager supports the Cisco Unified Wireless IP Phone 7925G. If your Cisco Unified Communications Manager does not support the Cisco Unified Wireless IP Phone 7925G, you will need to upgrade to a Cisco Unified Communications Manager release that supports the phone and/or install a device pack that will add the support for the phone.
Table 1: Cisco Unified Communications Manager Release Requirements for Cisco Unified Wireless IP Phone 7925G Support
CUCM Release
Minimum Service Release (SR) Required
DevicePack Required?
DevicePack Minimum Release
Notes
4.1(1) - 4.1(3)
-
Yes
4.1(82)
Install device pack
4.2(1) - 4.2(3)
-
Yes
4.2(3.55)
Install device pack
4.3(2)
-
Yes
4.3(2.08)
Install device pack
5.1(1) - 5.1(2)
5.1(3)
Yes
5.1.3.4114-2
Upgrade to 5.1(3) and install device pack
5.1(3)
-
Yes
5.1.3.4114-2
Install device pack
6.0(1)
-
Yes
***DevicePack Minimum Release 6.0.1.3112-1
Install device pack
6.1(1)
6.1(2)
Yes
6.1.2.1120-1
Upgrade to 6.1(2) and install device pack
6.1(2)
-
Yes
6.1.2.1120-1
Install device pack
7.0(1)
-
Yes
7.0.1.12004-1
Install device pack
http://www.cisco.com/web/software/282074289/23369/cmterm-7925-sccp.1-3-1-Readme.html
Hope this helps!
Rob