The rule: one helpful text, no sales pitch
A missed-call text back is safest when it is one informational text, sent from a registered business number, that names your business, answers the call and tells the caller how to opt out. Sales content changes the rules.
| Layer | What it asks of a missed-call text | Applies in |
|---|---|---|
| Federal law (TCPA, FCC rules) | Consent for autodialed texts; written consent for marketing texts | US |
| Carriers (CTIA, 10DLC registration) | Register your number; a clear opt-out; written agreement before promotional texts | US |
| State laws (example: Florida) | Written consent for automated sales texts | Some states |
| CASL | Consent for commercial texts, sender ID and an unsubscribe in each message | Canada |
Do I need consent to text someone who just called me?
For the first, informational reply, often not written consent. For marketing, yes. The FCC puts it this way:
"FCC rules ban text messages sent to a mobile phone using an autodialer unless the phone owner previously gave consent to receive the message or the message is sent for emergency purposes." (FCC)
"Commercial texts require written consent; for informational texts, your consent may be oral." (FCC)
Two points decide your case:
- Is it an "autodialer"? The Supreme Court held the device must be able "to store a telephone number using a random or sequential generator or to produce a telephone number using a random or sequential number generator" (Facebook v. Duguid, 2021). A tool that replies only to the number that just called you isn't built that way. Some state laws define automated systems differently, so don't rely on this alone.
- Is it marketing? Written consent means a signed agreement that "clearly authorizes the seller to deliver" advertisements or telemarketing to that number (47 CFR 64.1200(f)). A coupon or "book now and save" in the first text pushes it toward marketing. A stricter FCC rule requiring consent to one seller at a time never took effect: a federal appeals court vacated it on January 24, 2025 (Insurance Marketing Coalition v. FCC).
The FCC's rules don't mention missed-call text back by name. This is general information, not legal advice.
What the carriers expect
Carriers filter business texts, and their industry rules are stricter than "is it legal?" CTIA, the wireless industry group, sorts texts into three kinds:
"If a Consumer texts a Non-Consumer first and the Non-Consumer responds quickly with a single message, then it is likely conversational." (CTIA, 2023)
A missed call is a call, not a text, so your text starts the thread. Keep it to one message about the call. For anything promotional:
"Before a Non-Consumer sends promotional messages, the Consumer should agree in writing to receive promotional texts." (CTIA, 2023)
Register your number. Business texting from a standard 10-digit number in the US goes through A2P 10DLC registration: "Carriers block any A2P messaging traffic to US recipients using unregistered Twilio 10DLC numbers" (Twilio Docs). Ask your software provider whether it registers for you.
Setup: what the first text should say
- Send within a minute, from the number the customer dialed, so replies land in one thread.
- Name your business and say why you're texting: "Sorry we missed your call."
- Give the next step: "Reply with what you need, or we'll call you back today."
- Say how to opt out: "Reply STOP to opt out." CTIA says senders "should state in the message how and what words effect an opt-out" (CTIA).
- No offers, links to promotions or review requests in this text.
- Ask before more texts. For reminders or offers later, get the caller's agreement, in writing for promotions.
Honoring STOP
Federal rules list the words that always revoke consent: replies of "stop," "quit," "end," "revoke," "opt out," "cancel," or "unsubscribe" (47 CFR 64.1200(a)(10)). Opt-outs "must be honored within a reasonable time not to exceed ten business days" (47 CFR 64.1200(a)(10)). Make your software stop at once.
Changes take effect November 25, 2026: the FCC will let senders designate an exclusive way to opt out, such as a reply text, and narrow how far an opt-out from informational messages reaches (Federal Register 2026-21821).
State laws: Florida as the example
Florida's telephone solicitation law covers "a telephone call, text message, or voicemail transmission" made to solicit a sale (Fla. Stat. 501.059). An unsolicited sales text using "an automated system for the selection and dialing of telephone numbers" needs prior express written consent (Fla. Stat. 501.059(8)(a)). A call made "in response to an express request of the person called" isn't unsolicited (Fla. Stat. 501.059(1)(k)), but whether a missed call counts as that request is untested. Keep the reply about the call, with no offer. Other states have their own versions; check yours.
Missed call text back software: what to check
| Check | Why |
|---|---|
| Registers your number (10DLC) for you | Unregistered texts get blocked |
| Sends one text per missed call, not a sequence | Keeps it informational |
| Logs consent and opt-outs with dates | Your proof if a complaint comes |
| STOP ends all texts at once, across your numbers | Federal 10-business-day limit |
| Lets you edit the text and turn off promotions | You own the wording |
| Handles Canadian numbers separately | CASL rules differ |
Canada: CASL
A text that encourages buying from you is a commercial electronic message. It needs consent, and each one must identify you, give contact details and "set out an unsubscribe mechanism" (CASL s. 6).
- Implied consent covers "an inquiry or application, within the six-month period immediately before the day on which the message was sent" (CASL s. 10). A call asking about your services can be that inquiry.
- A message that solely "provides a quote or estimate" the person requested doesn't need consent, but still needs your name and unsubscribe (CASL s. 6(6)).
Details: CASL consent to text or email.
Example
US roofer, informational reply
A homeowner calls at 2:10 pm while the crew is on a roof. Text at 2:11: "Hi, it's Acme Roofing. Sorry we missed your call. Reply with your address and what's going on, or we'll call you back within the hour. Reply STOP to opt out." One text, no offer.
Florida HVAC, a spring promotion
The same company wants to text 500 past callers a $50 tune-up offer. That's a sales text sent by software: get written consent first, and don't count "they called us once" as consent.
Toronto plumber
A caller asks for a quote. Texting the quote within six months is covered by implied consent, and a requested quote is exempt. Each text still names the business and includes an unsubscribe.
Different for you?
- You want to know what missed calls cost before buying a tool: Missed calls: what they cost.
- You'd rather answer every call live or with AI: AI receptionist for a small business.
- Your callers are in Canada: CASL consent to text or email.
- You want to text customers asking for reviews: Asking for reviews: the rules.
- You run a dental or medical office (patient texts have HIPAA limits): AI receptionist for a dental office.
- Web leads at night, not calls: Speed to lead.