Texting customers as an HVAC business: TCPA consent, STOP opt-outs, and A2P 10DLC registration explained (2026)

The short answer: if you text customers from a regular business number through any software, U.S. carriers require you to register your business and your texting use case (A2P 10DLC) first — expect modest one-time and monthly fees and a review that can take a few days to a few weeks. Replying to someone who just called you about their system is generally on solid footing if the text stays on topic, identifies you, and tells them how to opt out. And the moment someone texts STOP, you stop.

By the MyWorkFlo team · Published September 27, 2026 · Fees and timelines checked against the sources listed at the bottom the same day.

This is general information, not legal advice. Texting rules vary by state and change over time. Talk to a lawyer about your specific situation, especially before sending any marketing texts.

Why do carriers require A2P 10DLC registration?

"A2P 10DLC" stands for application-to-person messaging over a 10-digit long code — a normal-looking business phone number sending texts through software rather than someone's personal phone. Twilio describes it as the standard U.S. carriers put in place "to ensure that SMS traffic to US end users through long code phone numbers is verified and consensual," because those routes were designed for person-to-person texting and started seeing abuse from spam.

Registration has two parts:

• Brand. Who you are: your legal business name, EIN, address, and website.
• Campaign. What you'll send and how people agree to it: the use case (for example, customer care and appointment scheduling), sample messages, how customers opt in, and your opt-out and help wording.

Skipping it isn't a real option. Registration is what keeps your messages from being filtered, and Twilio notes that businesses sending from a 10DLC number without registering pay additional carrier fees for unregistered traffic.

How long does registration take, and what does it cost?

All in, Twilio says the full process generally takes two to three weeks, though simpler registrations can clear faster. Separately, carriers add small per-message pass-through fees that change often. One 2026 change worth knowing: since June 30, 2026, Twilio rejects new campaign registrations submitted through its API that don't include a privacy policy URL and a terms and conditions URL.

Do you have consent to text someone who called you?

The federal law here is the Telephone Consumer Protection Act (TCPA), and the FCC's rules under it treat a text message as a "call." Two ideas matter most for an HVAC shop:

• Informational replies vs. marketing. Since 1992 the FCC has said that people who knowingly give out their number have invited calls at that number, absent instructions to the contrary. A customer who calls you about a broken AC has asked for a response about that AC. A text that answers that request — "Sorry we missed your call, what's going on?" — is in a very different category from a promotion.
• Marketing needs more. Seasonal tune-up offers, maintenance-plan pitches, and review blasts are marketing. Get clear, separate consent before sending those, and keep records of it.

Good practice for the reply itself: name your business, stay on the topic of their call, include opt-out instructions in the first message, and don't quietly add the number to a promotional list.

Which opt-out keywords do you have to honor?

Under FCC rules, customers can revoke consent by any reasonable means, and the words stop, quit, end, revoke, opt out, cancel, and unsubscribe are treated as definitive. Opt-outs must be honored within a reasonable time not to exceed 10 business days — but with software there's no reason to wait. You're allowed one confirmation text, which is presumed fine if it's sent within five minutes. After that, nothing.

• START (or UNSTOP) is the standard way a customer opts back in.
• HELP should get a short reply naming your business and how to opt out.
• People don't always use keywords. If a customer writes "please stop texting me," treat it as an opt-out.

Are there quiet hours for business texting?

Federal rules bar telephone solicitations to residential subscribers before 8 a.m. or after 9 p.m., local time where the recipient is. Some states are stricter — Florida's telemarketing law limits solicitation calls and texts to 8 a.m. to 8 p.m. The federal definition of "telephone solicitation" excludes messages sent with the person's prior express invitation or permission, which is why a reply to someone who just called you with no heat at 11 p.m. is treated differently from a promotional text at that hour. Still, schedule any marketing well inside those windows, and check your state's rules.

What should your privacy policy and terms say?

Carriers review these during campaign registration, and missing language is a common reason for rejection. Twilio's guidance points to:

• A clear statement that mobile numbers and texting opt-in data are not shared, sold, or rented to third parties or affiliates for marketing or promotional purposes.
• What kinds of messages you send and how often (for example, "message frequency varies").
• "Message and data rates may apply."
• How to opt out ("Reply STOP to cancel") and how to get help ("Reply HELP").
• Both pages published at public URLs you can link in your registration.

How does MyWorkFlo handle texting compliance?

MyWorkFlo doesn't answer calls by voice and doesn't send marketing blasts. Your phone rings first; when a call goes unanswered, conditional call forwarding sends it to MyWorkFlo, which texts that caller back about their call. Here's what it does, as built:

• Opt-out wording in the first text. The missed-call text names your business and ends with "Reply STOP to opt out" (or the Spanish equivalent).
• STOP handling. A message that is just STOP, STOPALL, UNSUBSCRIBE, CANCEL, END, or QUIT closes that customer's conversations, cancels any pending messages waiting on approval, and is logged. MyWorkFlo sends nothing further — and if that customer has an upcoming appointment, your team is alerted to call them instead.
• Opted-out contacts are never texted again. If an opted-out customer calls and you miss it, the call is recorded but no text-back goes out.
• START and HELP. START or UNSTOP re-subscribes the number with one confirmation text; HELP or INFO gets a single reply naming your business, with the STOP notice.
• A2P first. You can configure everything in about 10 minutes, but texting real customers starts only after carriers approve your business registration. Carrier registration is part of setup, and we walk you through it.

Two honest limits: keyword detection matches a message that is only the keyword, so a sentence like "please stop texting me" needs a human to honor it; and MyWorkFlo doesn't hold replies for a quiet-hours window, because its texts respond to a customer who just called. Your business remains responsible for following the messaging laws that apply to you. More on the product side in our guides to missed-call text-back for HVAC and after-hours HVAC calls, and on cost in what an HVAC answering service costs.

Common questions

Or get the sample missed-call text on your own phone — no signup. Plans and trial details are on the pricing page; for other approaches, see AI vs a human answering service, how to answer missed HVAC calls, and MyWorkFlo alternatives.

Sources

• twilio.com — Programmable Messaging and A2P 10DLC — definition, why carriers require registration, fees for unregistered traffic (accessed Sep 27, 2026)
• twilio.com — Direct Standard and Low-Volume Standard Registration Guide — review timelines (accessed Sep 27, 2026)
• twilio.com changelog — privacy policy and terms URLs required for new campaigns from June 30, 2026
• twilio.com — Error 30932 and improving your chances of A2P 10DLC approval — privacy policy and terms requirements
• tychron.com — 10DLC campaign registration and TCR fees — brand, vetting, and monthly campaign fees (last verified by the publisher July 21, 2026)
• 47 CFR § 64.1200 (Cornell LII) — time-of-day rule, definition of telephone solicitation, revocation of consent within 10 business days, five-minute confirmation text
• Bryan Cave Leighton Paisner — FCC opt-out keyword list and April 11, 2025 effective date
• FCC 12-21 (2012 TCPA order), citing the 1992 TCPA Order, 7 FCC Rcd 8769, para. 31 — the FCC's finding that people who knowingly release their numbers have invited calls at that number
• Fla. Stat. § 501.616 — Florida's 8 a.m. to 8 p.m. solicitation window

Next: How much does an HVAC answering service cost in 2026? →