NEC SL2100 Caller ID Callback
21-01-20 Set to Automatic
21-01-22 Set to Local
21-01-22 Set to 7 Digits
21-26-01 Set to the Area Code that the system is located in-ie:712 or 515
21-27-01- Enter the local prefixes for calls that are local from the Telephone system- ie: 362,363,209 etc