Letter of Authorization (LOA)
A Letter of Authorization, or LOA, is a document that permits a carrier or service provider to act for a customer on a defined telephone-service request, most commonly a number port.
What an LOA does
For number porting, the LOA tells the current provider that the customer authorizes the new provider to request the transfer. It commonly identifies the customer or business, the telephone numbers in scope, the service address, and the person authorized to sign. The details need to match the current provider's account records.
An LOA is specific permission, not a general transfer of every service on an account. Its scope should be clear about which numbers and action it covers. A provider may request supporting account records or other proof in addition to the signed letter. Requirements vary by provider, region, and number type, so the receiving provider's current instructions control the submission.
Small inconsistencies can cause a request to be rejected or delayed. A trading name may differ from the legal customer name, a billing address may differ from the service address, or the signer may not appear as authorized on the account. Checking those fields against a recent carrier record before submission is usually more effective than guessing after a rejection.
Why it matters for AI phone calls
An AI phone deployment may require an existing business number to move to a carrier or telephony setup that can route calls to the agent. The LOA is part of the administrative path that preserves that number while its carrier control changes. It does not configure the AI agent, SIP trunk, call flow, or caller ID by itself.
Teams should treat an LOA as sensitive business documentation. Share it only through the provider's approved process, retain a clear record of what was authorized, and verify the final routing after the port completes. If only temporary call forwarding is being configured, a porting LOA may not be relevant because control of the number is not moving.