2026-08-04

PBX to VoIP migration checklist: 7 phases (2026)

Work through seven phases to leave your PBX: audit the old system, vet providers, prep the network, port numbers, run cutover and check week one.

You've decided to move off PBX hardware. Now you need the order of operations. This checklist is for small business owners and project leads, and it breaks the job into seven phases: audit the current system, prepare your network, port numbers, manage cutover and validate the switch.

If you want the reasoning behind each phase, our PBX to VoIP migration guide covers it. Still making the case to your boss or partners? 10 advantages of PBX to VoIP lays out what you stand to gain.

How the seven phases fit together

The order is audit, provider, network, porting, cutover scheduling, cutover day, then week-one validation. Inventory and network work come before the switch. Testing and review run through the end of the first week.

Phase 1: Audit what you have

Know exactly what you're replacing before you talk to a single provider. Skipping this is the biggest reason PBX migrations hit surprises, because nobody can plan around a line, integration or device that never got written down.

[ ] Inventory every extension, line and device on your current PBX
[ ] Map your call flows: who answers, where calls route, what happens after hours
[ ] List every system your phone setup touches, including your CRM, scheduling tool and helpdesk
[ ] Note any analog lines that are easy to forget, like fax machines, alarm panels, elevator phones and overhead paging
[ ] Record your current call volume and peak-call times
[ ] Confirm the account holder name and billing address on file with your current carrier
[ ] Check your current contract for an end date or early termination terms
[ ] Name one person to own the migration from start to finish

Phase 2: Choose a provider

Providers aren't built alike, and this choice shapes how smoothly the rest goes. Look past price. The cheapest quote is rarely the cheapest system once add-ons and fees are added back in.

[ ] Confirm AI answering is included in the plan, not a paid add-on
[ ] Confirm how usage such as AI answering and transcription is billed, by the second or rounded up to the minute
[ ] Ask how the provider handles network reliability and outages
[ ] Confirm compatibility with your CRM and other integrations
[ ] Get a clear answer on what onboarding and number porting support is included
[ ] Ask what happens if you need to add or remove users later
[ ] Read the contract term, renewal and early-termination language, and confirm how seat changes are handled

For the full list of questions to put to a provider before you sign, see 10 questions to ask potential VoIP providers.

Phase 3: Prep your network

Call quality depends on the network being ready before go-live, not after.

[ ] Run a bandwidth check and confirm headroom above your normal data traffic
[ ] Set up Quality of Service (QoS) so voice traffic is prioritized
[ ] Confirm wired connections at desks with heavy call volume
[ ] Verify Power over Ethernet (PoE) switches are in place if you're keeping desk phones
[ ] Confirm a backup connection or mobile failover plan in case your primary internet drops
[ ] Review firewall and security settings for VoIP traffic

Phase 4: Port your numbers

Porting is usually the slowest part of a migration. Start early, and don't cancel anything until the port is confirmed.

[ ] Submit your port request through your new provider
[ ] Double-check the account holder name and billing address match your old carrier's records exactly
[ ] Keep your existing service active until the port is fully confirmed
[ ] Update your E911 address in the new system
[ ] Set a target port date with buffer room in case of delays
[ ] Notify staff of the target date so nobody is surprised by a brief change in call behavior

Phase 5: Schedule cutover

A cutover plan separates a smooth switch from a disruptive one. Everything in the earlier phases exists to make this day boring, and boring is what you want when the phones change underneath a working business.

[ ] Pick a low-traffic window, like a weekend or the start of a slow day
[ ] Assign one person to own cutover day and watch for issues in real time
[ ] Test inbound and outbound call flows before flipping over
[ ] Test your auto attendant or AI voice agent greeting and routing
[ ] Confirm voicemail and call forwarding work as expected
[ ] Prepare a rollback plan in case something needs to revert
[ ] Notify staff, and any key customers or vendors who call your main line, of the change

Phase 6: Cutover day

[ ] Confirm the number port has completed
[ ] Place live test calls on the new system
[ ] Verify caller ID displays correctly on outbound calls
[ ] Confirm integrations are syncing call data to your CRM or helpdesk
[ ] Verify your E911 address is correct with your new provider
[ ] Decommission or repurpose old PBX hardware
[ ] Watch call volume and quality closely for the first few hours

Phase 7: Week one validation

Small problems surface in the first week. A cutover can look flawless on day one and still hide a misrouted extension or a broken sync that nobody catches until a customer mentions it. Don't skip this phase.

[ ] Review call logs for missed or misrouted calls
[ ] Confirm voicemail-to-email or transcription is working
[ ] Check that integration records are updating correctly
[ ] Collect staff feedback on any rough edges with the new system
[ ] Confirm after-hours and AI answering behave as expected
[ ] Close out your old carrier account only after everything checks out

Mistakes this checklist prevents

Most PBX migration trouble traces back to a skipped step, not a step that went wrong. Forgotten analog lines, disconnected integrations and untrained staff cause more disruption than the phone switch itself. The audit, network and testing phases are there to catch those before callers do.

Connected-system features work through your existing CRM or business system and depend on that system offering a compatible API. Availability varies by provider.

Where CallSprout fits in

We work through this checklist with you instead of handing it over and disappearing. That means help with the audit, the provider comparison, the port and the cutover itself, and we stay involved through week one.

Sage, our AI voice agent, is available on every CallSprout plan, so you aren't moving to a phone system that still sends after-hours calls to voicemail. Pricing is transparent and published. Sage usage is $0.39 per minute after the first 30 seconds of each call are free, billed by the second. AI Transcription is $0.0198 per minute. Browse the CallSprout platform or check the pricing page for the full breakdown.

Frequently asked questions

Is this checklist enough to complete a full VoIP implementation on my own?

For most small businesses, yes, especially with a provider that supports you through porting and cutover. Larger or multi-location businesses may want a dedicated project owner internally, but the phases here cover what a complete implementation needs.

What is the difference between a PBX replacement and a partial upgrade?

A PBX replacement moves your phone system entirely to the cloud, including call routing, voicemail and any AI answering. A partial upgrade might add features like texting or call recording on top of your existing PBX without replacing the core hardware. This checklist assumes a full replacement.

How far in advance should I start working through this checklist?

Start the pre-migration audit as soon as you're seriously considering a switch, well before you pick a cutover date. Number porting depends on your current carrier's process, so the earlier you start Phase 4, the more buffer you have if anything runs long.

What should a VoIP migration checklist include?

It should cover the seven phases in this article: pre-migration audit, provider selection, network preparation, number porting, cutover planning, cutover day and week-one validation.

How long does a PBX to VoIP migration take?

This checklist doesn't set one universal timeline. It covers starting the audit before choosing a cutover date, beginning number porting early, adding buffer around the target port date and validating the system through week one.

Can I keep my phone numbers when migrating from PBX to VoIP?

This checklist covers submitting a number port through the new provider, keeping existing service active until the port is confirmed, and confirming completion before cutover.