A letter of authorization (LOA) is a signed document that gives a provider permission to act on your behalf with another party. In telecom and IT it appears in three common places: moving phone numbers to a new carrier, letting a network provider route or announce IP addresses you hold, and authorizing a cross-connect to your equipment in a data center. The exact form and rules depend on the provider, the type of request and the country.
At a glance
- An LOA authorizes a provider to request or perform something on your behalf with another party.
- For number ports, it lets the new provider ask the current provider to release your numbers.
- For IP addresses, it lets a network provider route or announce prefixes you hold.
- In data centers, an LOA-CFA identifies the exact port or panel position for a cross-connect.
- Details that don’t match the other party’s records are a common reason for delays and rejections.
What problem it solves
Providers need proof that a request comes from someone entitled to make it. Without it, numbers could be ported away by fraudsters, IP addresses could be announced by a network that has no right to them, and cross-connects could be patched into someone else’s equipment. The LOA is the written proof that the holder of the numbers, addresses or port has approved the request.
For buyers, getting the LOA right is mostly about avoiding delay. A port rejected because the suite number or business name differs from the old carrier’s records can push a cutover back days or weeks, which matters when a phone system migration or office move is scheduled around it.
How it works
Number porting. When you move numbers to a new carrier as part of local number portability (LNP), you sign an LOA (often called a letter of agency in this context) naming the numbers, the current carrier, the account number, the authorized name and the service address. The new carrier submits the port request. If the current carrier accepts it, it returns a firm order commitment (FOC) date that schedules the port; the port still has to be activated and verified on that date. Requirements vary by carrier and country, and many carriers also ask for a recent bill or a port-out PIN.
IP addresses. If you hold your own IPv4 or IPv6 address space, or are moving provider-assigned space with permission, a network provider will often ask for an LOA before routing it or announcing it with Border Gateway Protocol (BGP). Many providers also check routing registry entries and RPKI route origin authorizations, which the address holder controls.
Cross-connects. In a colocation facility, the party that owns a port or patch panel position issues an LOA-CFA identifying it, so the data center operator can run a cross-connect to it. These usually carry an expiry date set by the facility.
Whatever the type, the LOA should be signed by someone with authority, use details that match the other party’s records, and cover only the specific request. For phone number moves during a voice migration, our SIP trunking solution page covers the wider process.
When it matters for buyers
- Changing phone providers. Number ports generally start with an LOA; plan the port before the cutover date.
- Opening or moving an office. Ports and circuit cross-connects both depend on correct paperwork.
- Bringing your own IP space. Multi-provider internet with your own addresses requires each provider to accept your prefixes.
- Data center moves and new carriers. Each new cross-connect needs an LOA-CFA from the party that owns the port.
- After an acquisition. Accounts in the old company’s name may need updating before an LOA will be accepted.
Questions to ask vendors
- Who prepares the LOA, and will you review our current provider’s records before submitting it?
- What supporting documents do you need, such as a recent bill or a port-out PIN?
- How long do ports usually take with our current carrier, and how will we get the FOC date?
- For IP addresses, what do you need beyond the LOA, such as routing registry or RPKI entries?
- For cross-connects, how long is your LOA-CFA valid, and who orders the cross-connect?
- Can numbers or services be ported in stages to reduce cutover risk?
How it differs from local number portability
Local number portability (LNP) is the right and process that lets you keep a phone number when you change providers. An LOA is one document within that process: the authorization that lets the new provider start it. The LOA also has uses outside number porting, such as IP address announcements and data center cross-connects, which LNP does not cover.