What Is an LSR? Local Service Request Explained

An LSR (Local Service Request) is the standardized order form the gaining carrier submits to the losing carrier to initiate a number port. It is the carrier-to-carrier instrument behind every port: your LOA is the written consent, and the LSR is what actually moves between the two networks. Every field on the LSR must match the losing carrier’s records — when one field doesn’t, the port is rejected, which is why LSR errors are the single biggest cause of porting delays.

The acronym collides with other industries, so to be clear: in telecom, LSR means Local Service Request, the porting order — nothing to do with any other LSR you may have googled your way past. You never fill one out yourself; your new carrier generates it from your port request. But because the LSR is built from the account details you provide, the quality of your information determines whether the port sails through or stalls. SIPNEX is an FCC-licensed carrier that prepares and submits LSRs daily, so this is the view from the desk where rejections actually land.

One port, three documents: port order, LOA, and LSR

A port involves three distinct artifacts, and confusing them is where most misunderstandings start:

The port order is what you see: the request you open with the gaining carrier listing the numbers you want to move. It is a customer-facing ticket, not an industry instrument.

The LOA (Letter of Authorization) is your consent. It authorizes the gaining carrier to act on your behalf to port the listed numbers, and it carries the authorized name, business name, the numbers, your current carrier’s account information, and your signature — electronic or wet. The LOA backs the port but does not itself travel to the losing carrier as the order.

The LSR is the formal inter-carrier order generated from the two documents above. The gaining carrier submits it to the losing carrier, who checks it against their CSR (Customer Service Record) — the account file as they have it. If everything validates, the losing carrier issues a FOC (Firm Order Commitment) confirming the release date. On that date the number is activated in the NPAC, routing cuts over, and the port is done. The full six-step sequence, timelines included, is in our number porting guide.

One scope note: this flow is the wireline and VoIP world. Wireless-to-wireless ports run on a different, near-real-time inter-carrier process, which is why a simple cell-to-cell port typically completes within hours while business ports are measured in days.

The fields a losing carrier validates

The LSR succeeds or fails on data matching. The key fields:

• The telephone number(s) being ported.
• The BTN (Billing Telephone Number) — the main or primary number on the account, sometimes called the ATN. If you are porting the BTN itself while other numbers stay behind, flag it early; the losing carrier has to reassign a new BTN before releasing yours.
• The account number with the losing carrier.
• The PIN or passcode, where the carrier uses one. Note that a porting PIN can be different from the PIN you use to discuss the account, especially where a port freeze is in place.
• The authorized end-user name — exactly as it appears on the CSR.
• The service address as listed with the current carrier, not where you actually sit today if the records were never updated.

The reference document is always the losing carrier’s CSR, not your memory and not your latest invoice. A service address submitted as “100 Main St” fails against a CSR that reads “100 Main St, Suite 210” — and if the account was opened at an office you have since moved out of, the address that validates is the old one, however wrong it feels to write down. The cheapest insurance in porting is a five-minute call to your current carrier to read back the exact name, account number, service address, and PIN before anything is submitted. Also be aware that many losing carriers treat an LOA as stale after roughly 30 days, so don’t gather signatures months before you intend to port.

Rejections and supplements: how one typo eats a week

When an LSR fails validation, the losing carrier rejects it with a reason code — wrong account number, name mismatch, address mismatch, missing PIN. They do not fix it for you. The gaining carrier corrects the data and resubmits, a cycle the industry calls a supplement. Each cycle costs days: the corrected LSR re-enters the losing carrier’s review queue, and any FOC date already on the table can be reset.

This is the mechanism behind the common port delays every guide warns about. The losing carrier is not blocking the port — FCC rules prohibit refusing a valid request — it is procedurally rejecting an order that does not match its records, exactly as the process allows. A single-character typo carries the same penalty as a wholly wrong account number. Multiply a rejection cycle or two across a multi-number business account and the gap between “porting is fast” and “my port took three weeks” is fully explained, with no villain required.

The operational takeaways: verify against the CSR before submission, clear any pending orders on the old account, and identify BTN conflicts up front. Ports that validate on the first pass are boring — which is the goal.

The FCC rules that shape the LSR

The LSR is not just industry custom; a stack of FCC decisions defines how it works for simple ports:

Four-field validation (2007). For a simple port, the losing carrier may validate the request against no more than four fields: the 10-digit telephone number, the account number, the 5-digit ZIP code, and the passcode or PIN if one applies. A losing carrier cannot pile on extra validation hurdles for a simple port.

Standardized fields (FCC Order 10-85, 2010). The FCC adopted the industry implementation plan defining 14 standardized LSR data fields for simple ports, along with the provisioning flows that make fast simple ports possible.

There is also the famous one-business-day interval (FCC Order 09-41), which clocks only the losing carrier’s turnaround on a qualifying simple-port LSR — where the rest of a real port’s days go is broken down in the timeline section of our porting guide. One caveat keeps all of these rules honest: the FCC’s definition of a “simple” port is narrow — a single-line account, no complex switch translations, no reseller involved — and most multi-number business accounts do not qualify.

Frequently asked questions

SIPNEX handles the entire LSR lifecycle as part of number porting onto our network — we build the LSR from your LOA, pre-check it against your losing carrier’s records, work any supplements, and coordinate the FOC date so cutover lands when you want it. No port-in or port-out fees on US numbers. Have us pre-check your port details or review our rates first.