The sixty-second answer
Days to weeks, and your new provider does not control the clock. The carrier you are leaving validates the request, so their records set the pace. In a properly planned move the number keeps ringing the entire time and switches at an agreed cutover moment. Mismatched paperwork is what causes delay.
Why nobody can honestly give you a date up front
Moving a business number is not a technical job. It is a records job. Your new provider submits a request; the carrier you are leaving checks that request against what they have on file and either accepts it or rejects it. You are not waiting on engineering. You are waiting on a database that somebody else owns.
That is why a firm date offered before anyone has looked at your current bill is not worth much. Under section 74.01 of the Competition Act, a performance claim has to be based on an adequate and proper test, and the burden of proving that test sits on the person making the claim [4]. A provider who has never seen your account has not tested anything. The honest version of the answer is a range with the reasons attached, which is what this page gives you.
What is actually being moved
Your number is not a piece of property you own outright. Canadian numbering resources are administered under regulatory oversight and assigned according to approved guidelines, with the numbering administrator handing blocks of numbers to carriers rather than to businesses [1]. The administrator assigns those code blocks to carriers in exchange areas and is explicitly unaware of which individual numbers a carrier has given to which customer [2].
The practical consequence matters. The only organisation that knows your number belongs to you is the carrier billing you for it. Every question about how fast it can move is really a question about how good their record of you is.
What sets the timeline
How many numbers. A single main number is the simplest case. A block of numbers, a mix of numbers from different original carriers, or numbers spread across several accounts each add a validation step.
Whether your details match. This is the big one, and it gets its own section below.
Whether the account is clean. An unpaid balance, a contract dispute, or a cancelled-then-reinstated account will stall a request that would otherwise be routine.
Who is authorised. The person named on the carrier's account has to be the person authorising the move. In a business that has changed hands, changed name, or had three office managers since the line was installed, that is frequently nobody who still works there.
What kind of number it is. Geographic numbers behave differently from non-geographic ones, because a geographic numbering plan area corresponds to a discrete geographic area while other codes are assigned for services that transcend geographic boundaries [2]. Numbers attached to alarm panels, elevators, fax machines and analogue equipment carry their own complications; those are covered in analogue lines on a hosted phone system.
The mismatch problem, which is most of the delay
The request has to match the losing carrier's file: legal business name, service address exactly as they recorded it, account number, and authorised contact. That file was often typed by someone in a call centre years ago. The address may have a suite number you do not use. The business name may be an old operating name. The account may still be in a previous owner's name.
One wrong character rejects the request, and a rejection does not just cost you a day. It costs you another full cycle of submit, validate, respond. Three rejections is how a move that should have taken a week turns into a month, and it is almost always avoidable.
So do this before anything is submitted: get a copy of your current account record from your existing carrier, in writing, showing the exact billing name, service address, account number, and every number on the account. Give that to the incoming provider unedited. Do not retype it from memory and do not tidy it up.
Does the number go dark during the move?
No, not in a properly planned move. Your existing service keeps running and the number keeps ringing while the request is processed. The switch happens at an agreed cutover moment, usually short and usually scheduled for when you are quiet.
What causes real outages is cancelling the old account first. People do it to avoid paying for two services in the same month, and it is the single most expensive mistake in this whole process, because a cancelled number can be returned to the pool and is then not yours to move. Pay for the overlap. It is short, and the alternative is losing the number on your van, your sign, and every invoice you have ever issued.
If you want the number to keep working while you evaluate a new system without committing to a move at all, that is a legitimate option and it is covered in switching phone systems without moving your numbers.
What to line up for cutover day
Your emergency address. This is not automatic and it is not a formality. Emergency services are local to specific geographic regions, and best-practice guidance for internet-based emergency calling is blunt that a caller's location has to be established before an emergency call is placed, with civic addresses validated before they are relied on to route calls [5]. Confirm in writing which civic address is registered on the new service, and test it.
Your hours and after-hours routing. Decide before the switch, not after. See after-hours and holiday call routing.
Who answers what. Extensions, ring groups, and transfers should exist before the number arrives, not be improvised on the day. Start with what a phone extension is.
Your hardware. Existing desk phones can often be reused. Whether yours can is covered in keeping your existing handsets.
A test call list. Someone outside the building calls the main number, each direct number, and the after-hours path, from a mobile, within the first hour. A full sequenced version of all of this is in the 30-day cutover runbook.
Two commercial notes
First, ask what happens to the request if it is rejected, and who pays for the resubmission. That question separates providers who do this weekly from providers who will hand the problem back to you.
Second, ask for the all-in monthly figure including anything mandatory. Subsection 74.01(1.3) of the Competition Act treats a price that is not attainable because of fixed obligatory charges as a false or misleading representation, unless those charges are imposed under an Act of Parliament or a provincial legislature [4]. Our own numbers are published on the pricing page rather than held behind a quote form. More questions worth asking are in questions to ask a hosted phone provider.
Where we sit
We move business numbers onto hosted phone systems for Canadian businesses, and what we will tell you at the start is a range and the reasons, not a date we cannot control. We ask for your current account record first, because that one document is what decides whether this takes days or weeks. We do not ask you to cancel anything until the number is confirmed on the new service.
Most of the 1.08 million small businesses in Canada [6] have nobody on staff whose job is to chase a carrier's records department, and reliable basic telephone service is treated in Canadian law as infrastructure rather than a luxury, which is the plain sense of the policy objectives in section 7 of the Telecommunications Act [3]. Keeping the number you have already spent years teaching people to dial is part of that.
If what you actually want to know is whether the number survives a change of premises rather than a change of provider, that is a different question with a different answer: see can I keep my phone number if I move offices.