Move everyone at once, not gradually. A trickle migration means running two lines in parallel indefinitely, and the whole difficulty of this project is how long you have to hold two things in your head.

The work has four parts, and only one of them is about clients.

Build the list. Everyone who has your number, not everyone on your caseload. Those are different lists, and the second one is longer.

Decide what happens to the message history on the old line before you switch anything off. This is the part people discover too late.

Send one message to everyone, on the same day, with the same wording.

Track who has actually used the new number, and chase the ones who haven't.

Practitioners who have moved a full caseload describe it as a week of admin and then nothing. The clients are not the hard part. The hard part is that the old line holds things you may need, and once it is closed it is closed.

Where do I start?

With a list, in a spreadsheet or a document, before you touch anything.

Three groups:

Active clients. Everyone currently on your books. This is the list you think you are working on.

Recent and dormant clients. People who finished a while ago, people on a break, people who might come back. They are the reason the old line has to stay alive longer than feels necessary, because they will come back through the number they remember.

Everyone else with your number. Referral sources, other clinicians, an EAP, a school, an insurer, a landlord, an accountant. Long tail, low volume, and the group most likely to be using the old number a year from now.

Put a column for "told" and a column for "seen on the new line". You will want both.

All at once, or in batches?

At once, with one exception.

Batching sounds safer and is not. It doubles the period where you are watching two lines, it makes the "have I told this person?" question a lookup rather than a yes, and it means the announcement is stale for half the list by the time it reaches the other half.

The exception is a client in an acute period. If someone is in the middle of something difficult, tell them in the session rather than in a batch send, and tell them again in writing. Not because the message is different, but because the change lands differently for someone who is currently relying on the line.

What happens to the messages already on the old line?

Decide this before you close anything, because it may not be recoverable afterwards.

Two questions.

First: do those messages form part of the clinical record? Ontario's psychotherapy College is explicit that out-of-session contact belongs there. The clinical record contains "A notation of all in-session and out-of-session contacts with a client or their authorized representative", and the published examples are "letters, emails, texts, and telephone calls" (CRPO 5.1). Where written exchanges are the therapy itself, registrants "include copies of correspondence and treatment-related communication in the clinical record" (3.4.6).

The social work College is looser — correspondence and messages sit under what a record "may include" rather than must — but it adds a line worth knowing before you decide what to keep: anything placed in the record "cannot be removed" (OCSWSSW 4.1.2).

What that means practically is that the notation is the obligation, and the message history is the evidence behind it. Neither survives a cancelled account on its own.

Second: can you get them out? Some services let you export a full message history; some let you export nothing at all, and you find out at cancellation. Do the export while the account is still open and paid, not during the notice period. Practitioners have described losing access to accounts abruptly, and an export you meant to do is worth nothing.

Whatever you export, store it wherever the rest of your records live, under the same retention rules, not in a downloads folder.

How do I know who has actually moved?

Watch the new line, not the old one.

A client is migrated when they have contacted you on the new number, not when you have told them about it. Those are weeks apart for some people and never for others.

Practically: keep the list, and after the first few weeks mark off everyone who has appeared on the new line. Whoever is left is your chase list. For most people the chase is a single line in an email — just checking you have my new number saved — and the number arrives a second time in a place they can find it.

The old line is your other instrument. If calls are still arriving there, the migration is not finished, regardless of what your spreadsheet says.

The clients who never move

There will be a few. They are not being difficult; they have a contact card they never edited.

Three things help, roughly in order:

• The old number's greeting stating the new one, slowly, twice

• A forward from the old number to the new one, if your setup allows it

• Asking directly, in person, and watching them do it on their phone

The last one feels heavy-handed and works better than everything else combined.

What it costs

Money: two lines running at once for the overlap period. That is the real price of doing this safely and it is worth paying.

Time: a day to build the list and export what needs exporting, an hour to send, and then a low trickle of chasing for a while.

Attention: the genuine cost. For the overlap period you are checking two places, which is precisely the thing you were trying to stop doing. Set an end date for the old line when you start, so the overlap is a phase and not a new normal.

The short version

List everyone who has your number — which is more people than are on your caseload. Export anything from the old service that belongs in a record, while the account is still open. Tell everyone on the same day. Then measure the move by who turns up on the new line, not by who you told, and keep the old number speaking until that trickle stops.

About Rivet

Rivet is a Canadian practice line built for therapists — a separate number for calls, texts and voicemail, with video sessions and clinical tools in the same place. Your data stays in Canada, and transcription runs on Rivet's own hardware rather than a third-party AI service.

One plan, $65 CAD a month, everything included. Fourteen-day trial, no card.

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