Someone called and asked about your service. You now have six months, not twenty-four.
CASL treats an inquiry and a purchase completely differently, and the gap between them is eighteen months.
If a customer calls and asks about your service, CASL gives you implied consent to send them commercial messages for six months from the inquiry. If they actually bought something, you get twenty-four months from the purchase. Those two windows get conflated constantly, and the shorter one is the one that applies to the case most businesses care about: the missed call you want to text back.
How long does implied consent last?
Six months after an inquiry or application. Twenty-four months after a purchase, a contract, or the acceptance of a business opportunity. Both run from the event, and a new qualifying transaction restarts the twenty-four month clock.
The practical shape of this is that a first-time caller, the most valuable call most service businesses receive, is the one carrying the shortest permission. Someone who has bought from you before is easier to message and less likely to need it.
| What the person did | Implied consent lasts | Runs from |
|---|---|---|
| Made an inquiry or application | 6 months | The inquiry |
| Purchased a product, good or service | 24 months | The purchase |
| Entered a written contract | 24 months | The contract |
| Accepted a business opportunity or investment | 24 months | The acceptance |
Each new qualifying transaction restarts the twenty-four month period. An inquiry does not restart a purchase window; it starts its own, shorter one.
Is a missed-call text-back a commercial electronic message?
Usually yes. A CEM is any electronic message that encourages participation in a commercial activity, and a text saying "sorry we missed you, here's a link to book" plainly does. The message is lawful because implied consent covers it, not because it falls outside CASL.
That distinction decides what has to be in the message. A CEM sent under implied consent still needs the required identification and a working unsubscribe mechanism. A text that is purely transactional, confirming an appointment the customer already made, sits differently, but the automated "we missed your call" follow-up is the commercial one.
It also decides what happens at month seven. Implied consent expires, and it expires silently. A list of numbers collected from inbound calls degrades continuously, which is a good argument for texting quickly and a bad argument for texting a database of everyone who ever rang.
Does CASL apply to business-to-business messages?
Yes. CASL applies to commercial electronic messages generally, and there is no blanket exemption for B2B. There are narrow exceptions (including messages between organizations that already have a relationship, and messages to a published business address that are relevant to the recipient's role) but they are exceptions, not a category-wide carve-out.
This surprises trades and contractors most, because a lot of their inbound calls are from property managers, other contractors and commercial clients. The instinct is that CASL is a consumer-spam law. It is not, and the penalties do not scale down for B2B.
An inquiry buys you six months of implied consent under CASL and a purchase buys twenty-four, which means the first-time caller, the most valuable call a service business gets, is also the one carrying the shortest permission to follow up.
The cleanest answer to a CASL window is not to need one: answer the call while the person is still on the line.
Start free pilotWhat this page does not cover
This is a reading of the legislation as it applies to an AI receptionist answering a business phone, not legal advice. Statutes are amended and regulators publish new guidance; check the source links, which are dated, and take advice on anything that matters.
- Express consent. This page is about implied consent. Express consent does not expire and is worth collecting where you can, with its own form and record-keeping requirements.
- The full exemption list. CASL has a number of narrow exemptions this page does not enumerate. If a message plan depends on one, read the section rather than a summary.
- Content and unsubscribe requirements. Consent is only one of three requirements. Identification and an unsubscribe mechanism are separate obligations not detailed here.
Questions this raises
- Can I text someone back after they call and hang up?
- If they made an inquiry, CASL gives you implied consent for six months from that inquiry. A missed call where nothing was said is a weaker case (there is no inquiry to point at) which is a reason to answer rather than to text.
- Does a phone call count as a commercial electronic message?
- No. CASL governs electronic messages such as email and SMS. Voice calls are regulated separately, principally through CRTC telemarketing rules and the National Do Not Call List.
- Does the six-month window restart if they call again?
- A new inquiry starts a new six-month period from that inquiry. It does not extend the original one retroactively, and it does not create a twenty-four month window; only a purchase or contract does that.
- Do we need an unsubscribe link in a text?
- A commercial electronic message sent under CASL requires a working unsubscribe mechanism and sender identification, regardless of whether consent is express or implied. The format can be adapted to SMS but the obligation does not disappear.
- Is B2B texting exempt from CASL?
- No. There are narrow exceptions, including some messages between organizations with an existing relationship, but there is no general business-to-business exemption.
Sources
- Canada's Anti-Spam Legislation: Guidance on Implied ConsentCRTCconsulted 2026-08-09
- Frequently Asked Questions about Canada's Anti-Spam LegislationCRTCconsulted 2026-08-09
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