Cortelco Colleague Owner's Instruction Manual page 23

If a local call, and its 7-digit number is displayed:
•
Pressing OPTIONS once will change it to a 10-digit format (your area code +
7digit number).
•
Pressing OPTIONS twice will change it to an 11-digit number (1 + your area
code + 7-digit telephone number).
•
Pressing OPTIONS three times will go back to the original 7-digit telephone
number
Original
656-5756
The LCD can only display 10 digit telephone numbers, when you change the format
to 11-digits, only the first 10 digits can be seen, but it will dial 11-digits after you
press DIAL.
If a long distance call, and its 10-digit number is displayed,
1. Pressing OPTIONS once will change it to an 11-digit number (1+ 3-digit area
code + 7-digit telephone number).
2. Pressing OPTIONS twice will remove the 3-digit area code and change to
display only the 7-digit telephone number.
3. Pressing OPTIONS three times will go back to the original 10-digit number
4. For example: your own area code is 205, and you are reviewing telephone
number 914-656-5756.
When the desired format of the telephone number is reached, press DIAL to dial
the displayed number.
Press Options Button Oncel
(914) 656-5756
20
Press Options Button Twicel
1+(914) 656-5756