I have changed the phone type several times via CCA. Works great. The only issue is changing a 7900 phone with a different series. 7900 phones support octo lines. As long as the line is dual, you can change to anything. If changing from 7900 to another type, you will have to change the octo line to dual and then change the phone.
The steps are below:
1. Disconnect the phone from the network which needs chancing.
2. Wait about 5 minutes. The phone needs to unregister.
3. Go into CCA and login. To verify that the phone is unregistered, goto MONITOR, TELEPHONY and click on Phones and Extensions.
4. Find the phone which needs replacing. The phone status should say UNREGISTERED or DECEASED.
5. If it does, then you can CONFIGURE, TELEPHONY, USERS/EXTENSION and you will be able to change the mac address and the phone type.
6. Once done, you can save the settings and you are done.