VoIP Number Porting: Keep Your Numbers

Written by Ivan Elias, Founder & Principal Advisor · Published September 14, 2026 · Updated September 14, 2026

Your phone numbers are your business’s most underrated asset. Losing them means reprinting, re-notifying, and re-earning the trust behind every customer who saved them. The good news: number porting is a solved problem — when it’s run correctly. Here’s how it works and where migrations actually go wrong.

How porting works, in one paragraph

You (or your advisor) submit a Letter of Authorization (LOA) to the winning provider, who files the port request with the losing carrier. The losing carrier has a window to accept or reject. Once accepted, a port date is set, and at that moment routing for the numbers flips from the old carrier to the new one — ideally overnight, ideally invisible to callers.

The six mistakes that cause outages

1. Cancelling service before the port completes. The #1 cause of lost numbers. Never cancel the old account until every number is confirmed on the new one.
2. LOA details that don’t match the carrier record. Name spelling, service address, account number or PIN mismatches trigger rejections that cost weeks. Pull a recent invoice and copy it exactly.
3. Porting numbers nobody inventoried. Hunt numbers, fax lines, alarm lines and toll-free numbers often live on separate accounts or can’t port at all. Inventory everything first.
4. Forgetting associated services. Alarm lines and some elevator/medical lines are often legally required to stay on traditional service — flag them before the port.
5. Cutting over hardware at the wrong time. Configure and test new phones before the port date; flip desk phones the morning after the port completes.
6. No rollback plan. In the rare failure, numbers return to the working old carrier — which is exactly why you don’t cancel early.

Timeline that works

• Week 0: inventory numbers, pull invoices, sign order with new provider.
• Week 1: LOA submitted; win-back offers from the old carrier start arriving (decide your answer in advance).
• Weeks 2–3: configure the new system, phones, call flows; run parallel testing.
• Weeks 3–4: FOC (firm order commitment) date set; cutover communications sent; port executes overnight; verify inbound/outbound on every number that morning.

Advisor tip: the win-back call

The moment your old carrier receives the port request, retention calls begin — usually with real discounts. There’s no harm in hearing the offer; there’s real harm in accepting vague promises verbally. If you want leverage, having signed competing quotes in hand is what makes those calls honest.