One of the most common questions businesses ask before switching providers is simple: how long will it actually take? A clear phone system migration timeline removes the guesswork, so you can plan the switch without worrying about downtime, missed calls, or disruption to customers.

Why Migration Timelines Vary

No two migrations are identical. The time it takes depends on:

• Number of users and phone numbers being migrated
• Whether numbers need to be ported from another provider
• How many physical sites or locations are involved
• Whether new hardware (desk phones, headsets) is required
• Integration requirements, such as CRM or Microsoft Teams

That said, most small and mid-sized UK businesses can expect a full migration to be complete within one to two weeks, with some providers — including Curo IP — completing it in as little as 5 working days.

The Typical Phone System Migration Timeline

Day 1–2: Discovery and Planning

Your provider audits your existing setup — current lines, number of users, call volumes, and any equipment connected to your existing system (such as alarms or payment terminals, particularly relevant if you’re migrating ahead of the PSTN switch-off). A migration plan is agreed, including a target go-live date.

Day 2–3: Number Porting Requests Submitted

If you’re keeping your existing business numbers, porting requests are submitted to your current provider. This step often has the longest lead time, since porting timescales are partly controlled by the losing provider rather than the new one.

Day 3–4: Platform Setup and Configuration

Your new cloud phone system is configured in the background — user accounts, call routing rules, voicemail, and any integrations with CRM or Microsoft Teams are set up. Because this happens on the new platform, it doesn’t affect your existing phone service.

Day 4–5: Hardware Delivery and Testing

If new handsets are required, they’re shipped and pre-configured wherever possible, so they work as soon as they’re plugged in. Test calls are run to confirm call quality, routing, and any integrations are working correctly.

Day 5: Go-Live

Ported numbers are switched over, and your team moves onto the new system. A well-planned migration is designed so this happens with no gap in service — calls that would have gone to your old system are simply routed to the new one instead.

After Go-Live: Support and Onboarding

In the days following go-live, most providers offer additional support to fine-tune call routing, train staff on new features, and resolve any minor issues quickly.

How to Avoid Delays During Migration

• Start early – especially if you’re migrating ahead of a PSTN switch-off deadline, since porting and planning take time
• Provide accurate account details – incorrect account numbers or billing names are the most common cause of porting delays
• Flag connected equipment early – alarms, payment terminals, or lift lines may need separate arrangements
• Confirm a rollback plan – a good provider will have a contingency in place in case anything needs adjusting on go-live day

Will There Be Any Downtime?

With proper planning, a phone system migration should involve little to no downtime. Numbers are typically ported at a scheduled point, often outside business hours, and calls are redirected automatically so customers experience no interruption. The biggest risk to downtime isn’t the migration itself — it’s leaving the switch too late and running into a PSTN or ISDN switch-off deadline unprepared. See our guide on the PSTN switch-off for more on those deadlines.

How Curo IP Manages the Migration Process

Curo IP handles the entire migration process end-to-end — from initial audit through to number porting, hardware setup, and staff onboarding — with most UK businesses fully live within 5 working days. Get a free quote and we’ll map out your exact migration timeline before you commit to anything.