Hi Roy,
You can set the auto registration directory numbers and partition under Cisco Unified CM and enable the auto registration. By Default when the phone comes online, it will get number in this range and partition. Call Manager will assign it "Default" Device pool. (this is default setup and can be checked under Device>Device Setting > Device Defaults)
You can customize this Default Device pool for auto registration. Under the "Default" DP you can apply the CUCM group. Create a CSS for auto registered phones and apply it under this device pool, there is option called CSS for auto registration. This way all auto registered phones will get Default DP and CSS you assign to this Default Device pool.
You can also create a new Device pool and assign correct CUCM group and CSS and then change the default Device Pool to this one under Device>Device Setting > Device Defaults. But this way you will need to change the Default Device pool for all the models in use.
Easiest way is to enable the auto registration and specify the number range, partition, external mask (if reqd.) etc. and then modify the Default Device pool and just change the required settings like CUCM group, CSS for auto registration etc.
Hope that helps.
Terry
Please mark the question answered if you have no other queries.
