How missed call text back works: the setup, the US texting rules and what it really costs

The short answer: missed call text back is an automation that sends a text to anyone whose call you didn't answer, usually within a minute, from your business number or a line connected to it. Your phone system notices the call ended without a live answer, passes the caller's number to a texting service, and that service sends a short message such as "Sorry we missed you, this is Oak Plumbing. What can we help with? You can also book here." When the caller replies, the conversation lands in your inbox, CRM or an AI assistant that can answer and book.

If you would rather have it built and run for you, that is our done-for-you missed call text back service.

Methodology: this is an editorial explainer, not a survey. Every price and rule below comes from the linked primary source, checked on October 31, 2026. Prices change; check the source before you budget.

How missed call text back works, step by step

1. A customer calls your business number. Nothing changes for them: same number, same ringing.
2. The system waits for an answer. On a cloud phone platform, the call rings your phones for a set time. In Twilio's <Dial> verb, for example, the default timeout is 30 seconds (Twilio Docs). GoHighLevel recommends an incoming call timeout of 10-20 seconds for its version of the feature (HighLevel Help).
3. It detects the miss. When the dialed leg ends, the platform reports why. Twilio's statuses include no-answer ("did not pick up before the timeout period passed"), busy and failed; a call that reached a person comes back as completed. Anything other than a live answer can trigger the text. One catch: if the call rings a cell phone whose own voicemail picks up, the platform sees an answered call. Keep the ring time shorter than the voicemail delay, or turn voicemail off on the phones being rung.
4. It sends the text. A webhook or workflow sends your message to the caller's number, often with their name filled in if they are already a contact.
5. It routes the reply. Replies go to your phone, a shared inbox, your CRM or field-service tool, or to an AI assistant that keeps the conversation going.

One technical point decides most of the design: the number that receives the call must be connected to the system that sends the text. That is easy with a new tracking number and takes a little more work if you want to keep the number already on your truck, website and Google profile.

Keep your number or use a new one?

Carrier guidance points the same way: CTIA's Messaging Principles say business texting should only be enabled on a number the sender has actually been assigned by a telecom or VoIP provider, after verifying that authority (CTIA). In practice, you can text-enable a number you control, not someone else's.

What the text should say, and what happens after a reply

The first message works best when it does three things: names your business, acknowledges the call, and gives one easy next step. For example:

"Hi, this is Oak Plumbing. Sorry we missed your call. What do you need help with? Or book a time here: [link]. Reply STOP to opt out."

• Name the business. The caller may not recognize the number the text comes from, especially with forwarding.
• Keep it about their call. A coupon, a promotion or a pitch for other services turns the text into marketing for carriers and possibly under the law (more on this below). A booking link is fine for the job they called about; keep it to that job.
• Ask one question or offer one link. "What do you need help with?" is easy to answer from a lock screen; a paragraph of options is not.
• Plan the reply. A text-back that nobody reads is worse than none. Route replies somewhere watched, with an instant alert for urgent words like "leak" or "emergency".

This is where AI earns its place. An AI assistant can read the reply, answer common questions, collect the address and job details, and offer real slots from your calendar, then hand the thread to a person when it needs one. The next step up is an AI receptionist that answers the call itself, so fewer calls are missed in the first place; the text-back then catches the rest. Our guide to what an AI receptionist costs covers that option, and we compare it with a staff hire in AI receptionist vs hiring a receptionist.

US rules: A2P 10DLC and the TCPA

A2P 10DLC registration

A2P 10DLC is "the standard that United States telecom carriers have put in place to ensure that SMS traffic to US end users through long code phone numbers is verified and consensual" (Twilio Docs). You register a brand (your business) and a campaign (what you send and why), including "how end users can opt-in, opt-out, and receive help," a description of the messages and sample messages. Registration lowers carrier filtering, and Twilio blocks messages to US numbers sent from a 10DLC number that is not associated with an approved A2P 10DLC campaign (Twilio error 30034). GoHighLevel also lists A2P 10DLC registration (or toll-free verification) as a requirement for its missed-call text back (HighLevel Help).

For a missed-call flow, the campaign description should say plainly that the business texts people who just called it and did not get an answer, and the sample messages should match what you actually send.

TCPA consent and opt-outs

The Telephone Consumer Protection Act and the FCC's rules at 47 CFR 64.1200 cover text messages as well as calls. The main points for a text-back:

• Autodialer consent. The rules require prior express consent for calls to wireless numbers made with an automatic telephone dialing system or an artificial or prerecorded voice (47 CFR 64.1200(a)(1)). In Facebook v. Duguid (2021), the Supreme Court held that a device counts as an autodialer only if it can store or produce numbers "using a random or sequential number generator" (Facebook, Inc. v. Duguid, No. 19-511). A system that only replies to the number that just called you does not use a random or sequential number generator, so under that test it is unlikely to count as an autodialer under federal law. Some state laws define autodialers more broadly.
• Telephone solicitations (time of day and Do Not Call). Telephone solicitations may not be sent before 8 a.m. or after 9 p.m. local time, or to numbers on the national Do Not Call registry. The definition excludes messages sent with the person's "prior express invitation or permission" or to someone with an established business relationship, which includes an inquiry about your products or services within the previous three months (47 CFR 64.1200(c), (f)(5), (f)(15)). A reply about the call someone just made is a different thing from a sales blast, and it stays that way only if the content stays about their call. Separately, marketing texts sent with an autodialer need prior express written consent (47 CFR 64.1200(a)(2)), and that paragraph has no established-business-relationship exception.
• Opt-outs today. Replies of "stop," "quit," "end," "revoke," "opt out," "cancel" or "unsubscribe" are per se valid revocations, other reasonable wording must be honored too, and requests must be honored within ten business days. A single confirmation text with no marketing content is allowed; if sent within five minutes it is presumed to fall within the consumer's consent (47 CFR 64.1200(a)(10)-(12)).
• Opt-outs from November 25, 2026. An FCC final rule published October 26, 2026 lets senders designate an exclusive opt-out method, such as replying with one of those standard words, as long as the method is clearly disclosed. For reply-based opt-outs, the rule says: "Text senders that designate a reply text message as the exclusive means to revoke consent can satisfy the disclosure obligation by including at least one of the standardized words contained in paragraph (a)(10)(ii) of this section in each text message so long as the text sender recognizes the use of any of the standardized words as a valid revocation request." It also lets a sender treat an opt-out from an informational text as covering only that category of informational messages (Federal Register, 91 FR 67214).

Carrier guidance lines up with this. CTIA calls a message "conversational" when the consumer starts the exchange and the business "simply responds," in which case "no additional permission is expected"; promotional texts should have the consumer's written agreement first (CTIA). Note that CTIA's example is a consumer who texts first; a phone call is close, but it isn't spelled out. That is why careful setups send one reply about the call, add an opt-out line, and keep follow-up sequences and promotions for people who have agreed to them.

Not legal advice. This section summarizes federal rules and industry guidance as published on October 31, 2026. State laws can be stricter, and your obligations depend on your business and message content. Check your setup with a qualified attorney.

What missed call text back costs

There are three layers: the phone number and texts, carrier registration, and the software or service that runs the flow. The first two are small. These are Twilio's US prices; GoHighLevel's help center says its LC Phone pricing "is precisely the same amount as Twilio" (HighLevel Help).

In other words, each single-segment text costs about 1.2 to 1.3 cents with the carrier fee. 300 one-segment texts cost about $3.50 to $4.00, or roughly $6 to $7 a month with the $1.15 number and a $1.50 low-volume campaign, before inbound replies. Long messages cost more because each segment is billed separately, and T-Mobile also charges a fee on inbound messages. Low-volume standard brands are for businesses with a Tax ID (EIN) sending fewer than 6,000 messages a day, and the $1.50 low-volume mixed campaign supports up to 2,000 segments a day toward T-Mobile; sole proprietor registration is for businesses without an EIN.

The software layer is where the money goes. GoHighLevel, which has missed-call text back built in, lists plans at $97 a month (Starter) and $297 a month (Unlimited), with a $497 plan above them, a 14-day free trial, and phone, SMS and other usage billed on top (GoHighLevel pricing). Building directly on Twilio has no platform fee but needs a developer to write and host the flow, the reply routing and the monitoring.

Whether any of this pays off depends on how many calls you miss and what a job is worth. Our free missed-call cost calculator lets you plug in your own numbers.

DIY or done-for-you: a comparison

When done-for-you makes sense

DIY is a fine choice if you already run your business on GoHighLevel or have a developer who knows Twilio. A managed setup makes more sense when:

• You want to keep your current number and don't want to deal with forwarding codes, hosted SMS paperwork or porting.
• Your 10DLC registration has already been rejected once, or you don't know how to describe the opt-in for a missed-call flow.
• You want replies to reach a person or an AI assistant fast, with someone monitoring that the texts actually go out.

Our missed call text back service includes A2P 10DLC registration, quiet hours, opt-out handling and monthly monitoring; carrier and SMS usage are shown on your quote.

FAQ

Is missed call text back legal in the US?

No federal rule addresses missed-call texts by name. The lowest-risk version is one prompt reply about the call the person just made: that is close to what carrier guidance calls a conversational message, and under the FCC's definitions it is a reply to an inquiry rather than a telephone solicitation. It is still not automatically exempt. Keep the first text about their call, identify your business, honor STOP and similar replies, and get written consent before any marketing sequence. State laws can be stricter, so check your setup with an attorney. This is not legal advice.

Can I keep my current number with missed call text back?

Yes, in one of two ways. A landline or toll-free number can often be text-enabled while your voice service stays where it is; Twilio's hosted SMS supports US and Canadian numbers but not mobile numbers. Otherwise, conditional forwarding sends unanswered calls to a text-enabled line, so customers still dial your number and the reply comes from that line.

Do I need A2P 10DLC registration for missed call text back?

If you text US customers from a regular 10-digit business number through a platform such as Twilio or GoHighLevel, yes. Registration covers your brand and a campaign that describes how people opt in, how they opt out and sample messages. Carriers filter unregistered 10DLC traffic, and Twilio blocks it.

How much does missed call text back cost per month?

The telecom part is small: at Twilio's US prices checked on October 31, 2026, a local number is $1.15 a month, each SMS segment is $0.0083 plus a carrier fee of up to $0.005, and a low-volume 10DLC campaign is $1.50 a month. The bigger costs are software, such as GoHighLevel from $97 a month, or a managed service, such as ours at $1,500 setup plus $297 a month.

Sources

1. Twilio Docs: TwiML <Dial> (timeout, DialCallStatus values), checked October 31, 2026
2. HighLevel Help: Where and how to configure the Missed Call Text Back feature (updated September 7, 2026)
3. Twilio Docs: Hosted Numbers / Hosted SMS
4. CTIA: Messaging Principles and Best Practices (May 2023)
5. Twilio Docs: A2P 10DLC
6. Twilio Docs: Error 30034, US A2P 10DLC message from an unregistered number, checked October 31, 2026
7. Twilio Help Center: Pricing and fees for A2P 10DLC service (TCR fees updated August 1, 2025), checked October 31, 2026
8. Twilio: US SMS pricing, checked October 31, 2026
9. Twilio: US voice pricing, checked October 31, 2026
10. HighLevel Help: HighLevel pricing guide (LC Phone pricing)
11. GoHighLevel: Pricing, checked October 31, 2026
12. eCFR: 47 CFR 64.1200, Delivery restrictions
13. Supreme Court of the United States: Facebook, Inc. v. Duguid, No. 19-511 (decided April 1, 2021)
14. Federal Register: Enhancing the Ability of Consumers To Control the Robocalls, 91 FR 67214 (final rule, effective November 25, 2026)

VLWritten by the VL Studio team. We build websites, apps, automations and AI receptionists for small businesses and founders in the US and Europe.