Letter of Agency or Letter of Authorization. A document you complete and return to your new carrier that authorizes the new carrier to act on your behalf when it comes to communications matters. This is normally obtained so that your new carrier can request Local Number Portability (LNP) from your previous carrier, transferring your number from the losing carrier to the new carrier.
Merriam-Webster Online Dictionary
LOA (abbreviation)length overall
LOA (Wikipedia)
LOA may stand for: