NPA 424 to Overlay NPA 310

Event typeOverlay
Area code310
Related code424
Latest letter1998-05-26
Mandatory date1999-04-17

Primary documents

LetterPublishedSubject

All documents are official NANPA planning letters (Tier A sources). This page consolidates every letter we have on record for this event; it is updated automatically when new letters are detected, with sensitive changes held for editorial review first.