Entries can be added from the base or the handset. The CID button is on the right of the control ring; the phonebook is on the left of that ring.
If you want to add a number from the Caller ID list to the phone book, press CID and use the up/down arrows to navigate to the call that you want to add. Then press Menu/Select. Select the line Store into Pb and press Menu/Select. You will be at the Edit Name Screen for the phonebook.
To enter a new item from scratch, press the Phonebook button. Then press Menu/Select and select the Create New submenu. Press Menu/Select and enter the name of the contact using the alphabet on the key pad. (For C, press 2 three times.) Press Menu/Select and enter the phone number as it is dialed (including a 1 if needed). If you need to add a pause in the number, press Redial/Pause. However, the entire number must be less than 20 digits (including the pause). Press Menu/Select again. If you enter the number from the handset, you will be prompted to select a ringtone to always use when you get a call from that number. Press Menu/Select again. Then press End (on the handset) or Play/Stop (on the base) to exit the menu system.
Uniden has the manuals available at their site, either from the product page or the support page. All DECT phone manuals are here: http://www.uniden.com/bin/venda?ex=co_disp-view&bsref=uniden&scat=dectphones_mnl
. The manuals are listed in numerical and alphabetical order. The direct link to the D1688 manual in English is http://www.uniden.com/content/ebiz/uniden/resources/ownersmanuals/D1688-2om.pdf
I hope this helps.