Panasonic KX-TDA50 Features Manual page 601

If the telephone number does not contain an area code programmed here, it is modified based on the Long
Distance Code settings.
Area Code (for Local / International Call Data 1–10)
Specifies the leading number (area code) to look for in the incoming caller's number.
Default
Not stored.
Value Range
Max. 6 digits (consisting of 0–9, *, and #)
Programming References
None
Feature Guide References
1.16.1 Caller ID
Removed Number of Digits
Specifies the number of digits to be removed from the beginning of the incoming caller's number.
Default
Local / International Call Data 1–10: 3
Long Distance Code: 0
Value Range
0–9
Programming References
None
Feature Guide References
1.16.1 Caller ID
Added Number
Specifies the number to be added to the incoming caller's number in the place of the removed digits.
Default
Local / International Call Data 1–10: Not stored.
Long Distance Code: 1 (fixed)
Value Range
Max. 4 digits (consisting of 0–9, *, and #)
4.12 Feature [6]
Feature Guide 601