Yes, you can block a number, and therapists do. The thing to be clear about is that blocking a current client is a clinical decision with clinical consequences, not a settings change — and it is the last step in a sequence, not the first.

The sequence that most practitioners work through, in order:

1. Name it in session. The contact pattern is material. Bring it into the room before you do anything to the phone.

2. Restate the policy in writing — which channel, which hours, what you will and will not respond to, and what to do instead when something cannot wait.

3. Narrow the channel rather than closing it. Move to one route you do check, at stated times, and stop replying on the others.

4. Say what happens if it continues, plainly, so nothing that follows is a surprise.

5. Then, if it continues, restrict or block — and document what you did and why.

Skipping to step five is what makes this dangerous. A blocked number is silent in both directions, and silence is indistinguishable from abandonment to the person on the other end.

When blocking is straightforward

Former clients, where the work has properly ended and contact has become intrusive. Practitioners describe this without much agonising, and the same threads describe having had to block several numbers after a bad period.

Non-clients. Parents of adult clients, ex-partners, someone who obtained your number and is not in your care. There is no therapeutic relationship to protect, and the boundary question is much simpler.

Anything abusive or threatening. Practitioners describe threats and abusive calls, and in some cases involving police. Do not treat that as a clinical boundary exercise. Get support, and treat your own safety as the deciding consideration.

When it is not straightforward

An active client, in a live therapeutic relationship, who is using the phone in a way you cannot sustain. That is the hard case, and it is nearly always about something other than the phone.

Two things are true at once. You are not obliged to be available at all hours, and no policy makes you responsible for a channel you never agreed to. Also: withdrawing contact abruptly from someone who is currently in your care is a clinical event that can be harmful, and it looks very different in a complaint than it feels at 2am.

What the Ontario Colleges publish about ending or interrupting contact is narrower than "you can't" and more demanding than "it's your line."

The psychotherapy College treats discontinuing services as a communicated, documented act. Registrants "clearly communicate and document the reason(s) for discontinuing services and the conversation they have with the client," and where the client still wants treatment they "make reasonable efforts to provide referrals to other providers" (CRPO Professional Practice Standards, Standard 6.3).

The social work College asks for notice and arrangements. Registrants who anticipate an interruption of service "shall ensure that clients are notified promptly and that arrangements are made for the termination, transfer, referral, or continuation of service in accordance with clients' needs and preferences" (OCSWSSW, Interpretation 3.12).

The psychology and behaviour analysis College is the one that names the exit. Services "may only be discontinued if reasonable efforts are made to secure alternative services, the client is afforded a fair chance to arrange alternatives, or the continuation of services would pose a serious personal or professional risk to the registrant" (CPBAO Standards of Professional Conduct, Standard 2.3).

That last clause is the one that covers the genuinely unsafe case. The two before it describe what the ordinary case is supposed to look like: notice, a referral, a documented conversation. None of that is a block, and all of it is easier to show afterwards than a silent number is to explain.

What to do instead of blocking, first

Stop replying outside your stated hours, consistently. The most common cause of escalating contact is intermittent response: sometimes you answer at 11pm and sometimes you do not, which is the pattern most likely to produce more contact, not less.

Silence the practice line rather than the person. Quiet hours on the line achieve most of what blocking achieves, without singling anyone out and without cutting anybody off in an emergency.

Send one clear message rather than a series. Practitioners who have done this well describe sending a single text that states the boundary explicitly and names what to do instead — then holding it.

Book it into a session. "I want to talk about the texting when we meet" both answers the person and moves the conversation to the right place.

If you do block

Write it down. What happened, what you had already tried, what you told the client, when you blocked, and what alternative routes remain open. If this is ever reviewed, the record is what you have.

Leave a route open, and tell them what it is. A blocked phone number with a working email address is a boundary. A blocked everything is a disappearance.

Say what happens to the therapeutic relationship. Blocking a channel and ending the work are different decisions, and the client should not have to infer which one you have made.

Make the crisis alternative concrete. Before the block, not after — and specific, so nobody is left guessing what to do in a bad hour.

The part that is easy to lose

Everyone in this position is exhausted, and blocking feels like the only lever because it is the only one that acts immediately. It is worth noticing that the lever which actually works — a stated policy, held consistently, said out loud in session — is slow, and that the reason it feels insufficient is usually that it has never been held consistently for long enough to work.

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