With the 8845 handset they appear to have 10 x line keys but apparently only the 5 on the left hand side can be programmed. If this is true is it possible for the 5 x keys on the right hand side not to display anything or is this a default setting and where can I find what is actually the default, or are they soft keys and change?
In regards to the keys on the left and right-hand side of the 8845, this is essentially the same as 8841, 9971, etc.
Correct, only the 5 keys on the left can be programmed for DNs, speed-dial, and so forth. The other 5 keys on the right cannot be configured as far as I am aware. Source: https://learningnetwork.cisco.com/thread/82889
By default, in the on-hook state, the top right button (handset icon) can be used to go off-hook/on-hook, and below that is a Recents button to review past calls. The layout of these buttons may slightly change depending on the phone state. For example, if you are already on a call, another button with a handset icon will appear, which allows you to start a New Call and place the existing call on hold.
Just wanted to add a note to the good tips from Timothy (+5).
The behavior you are seeing can now be changed to add the 5 additional keys with the installation of new CUCM Device Packs that contain firmware 11-5-1 as shown below;
The buttons on the left and right of the phone screen can be set up as line buttons, giving up to five more line keys. Users see an alert for an incoming call.
Enhanced line mode is supported on Cisco Unified Communications Manager 9.1(2), 10.5(2), and 11.0(1) and any higher releases that are generally available. The latest Device Package is required. You can set the line mode in the Product Specific Configuration Layout portion of the Device Configuration window in Cisco Unified Communications Manager.
Enhanced line mode supports most but not all features with Firmware Release 11.5(1).