I have Uniden phones connected to my 3 Obi's.
When a call comes in on Google Voice they display 11 digits for the caller id. If the number is in my contact list it will display the name from the contact, but it still displays 11 digits even though some contacts only have 7 digits in the contact.
On all 3 Obi's, when a call comes in on the LINE port it only displays 7 digits because I set my local area code in the phone's menu. By setting the area code the phone itself filters 10 digit numbers and displays them as 7 digits. If you want the phone to display all 10 digits you should delete your area code from the phone's setup.
From my phone's manual - Dect 1560/1580
Seven-digit dialing
If you can make a local call by dialing only seven digits instead of ten, you can tell the phone to hide your local area code in the Caller ID list; any calls from outside your area code will show all ten digits. This setting applies to the base and all handsets currently connected to the same base.
To program your local area code:
Press Menu /Select .
Select the Global Setup menu, and then the Area Code submenu.
Use the number keypad (0 through 9) to enter a three-digit area code. If an area code has already been stored, it appears in the display. Press Clea r/Int 'com to delete the stored code, and then enter a new one.
Press Menu /Select . You will hear a confirmation tone.
Note: If you have multiple bases, select the base before programming the area code (see page 15).
The phone uses the stored area code as a filter. When a call comes in, the phone compares the incoming area code to the code programmed on the phone. If the two codes match, the handset hides the area code in the Caller ID list.
When you are reviewing the Caller ID list, you can show the hidden area code by pressing #. Press # again to hide the area code.
When you dial from a Caller ID record or store a Caller ID record in the phonebook, the phone dials or stores the digits exactly as they appear on the display. If you need to use ten digits, be sure to press # to show the area code before you dial or store the number. (See page 2 7 to store a Caller ID record in the phonebook.)