Settings > Display and Backlight > Showing of Names Only

Showing of Names Only
If showing of only names for lists/calls is switched on, only the name of the call partner (if known) is displayed for incoming external calls and in caller, calls and redial lists.
If showing of only names for calls/lists is switched off, the phone number and the name of the call partner are shown alternately.
 
Proceed as follows:
Using COMfortel Set (page Settings/functions > Display, check box For lists/calls show names only)
Using the telephone (menu settings > display > lists/calls)

COMfortel 1200 - Firmware V2.2 - COMfortel Set V3.16 - Advanced Information V07 02/2019