What is missed-call textback?

An automation that instantly texts anyone whose call your business missed — typically 'Sorry we missed you! How can we help?' — capturing the lead before they dial a competitor. It's often the highest-ROI automation a local business can install.

Do I need A2P registration to send textbacks in the US?

Yes. US carriers require A2P 10DLC registration (brand + campaign) for business SMS. Unregistered traffic gets filtered or blocked. Registration takes a few days through Twilio or GoHighLevel's LC Phone and is non-optional for production.

Can an AI agent call the missed caller back?

Yes — the upgrade path from textback is an AI callback: a Retell voice agent rings the lead back within a minute, answers questions and books directly into the calendar. Text captures the lead; the voice agent converts it.

Missed-Call Textback with GoHighLevel + Retell: The Complete Build

TL;DR: Missed-call textback = when your business misses a call, the caller instantly gets a text ("Sorry we missed you — how can we help?"). It's the highest-ROI automation a local business can install, takes an afternoon in GoHighLevel, and the 2026 upgrade is an AI voice agent that calls the lead back within 60 seconds and books them. Here's the full build, including the A2P compliance step everyone forgets.

Around 40% of calls to local businesses go unanswered — after hours, mid-job, lunch. Every one of those callers had intent right now, and most dial the next Google result within minutes. Textback catches them before they do. I've built this system dozens of times for US service businesses; this is the exact recipe.

The basic build (GoHighLevel, ~1 afternoon)

Prerequisites: a GHL sub-account with a phone number (LC Phone or Twilio), and — non-negotiable — A2P 10DLC registration (below).

Trigger: Automation → new workflow → trigger Call Status = Missed (incoming calls that weren't answered).
Guard conditions: only fire for first-time missed calls in a window (avoid double-texting someone who calls twice), and respect quiet hours (no 2am texts — queue until morning).
The message. Short, human, useful:

"Hi, this is {{business}} — sorry we missed your call! How can we help? Reply here or grab a time: {{booking_link}}"
Route the reply. Replies land in GHL Conversations; assign to a user, ping the owner's phone via the mobile app, and tag the contact missed-call-lead.
The follow-up nobody adds: if no reply in 30 minutes, send one (one!) nudge. Then stop — persistence reads as spam.

That's the whole v1. It'll recover leads in week one.

The A2P 10DLC step (skip this and nothing sends)

US carriers require registered brand + campaign for application-to-person SMS. Unregistered messages are silently filtered — the automation "works", the texts never arrive, and nobody notices for weeks.

Register via GHL (Settings → Phone Numbers → Trust Center) or Twilio Console (Trust Hub) with real business details (EIN, website, sample messages including opt-out language).
Budget 2–7 days for approval and small registration/monthly fees.
Include Reply STOP to opt out handling — GHL manages this automatically once configured.

The 2026 upgrade: AI callback

Text captures the lead; a voice agent converts it. The upgraded flow:

Missed call → instant textback (as above)
           → n8n webhook → wait 60s → Retell AI outbound call to the lead
              → agent: "Hi, you just called {{business}} — I can help right now
                 or book you in. What did you need?"
              → books into the GHL calendar mid-call → SMS confirmation
              → transcript + outcome written back to the GHL contact

Why the 60-second wait: an instant robocall-back feels uncanny; a text followed by a near-immediate helpful call feels like great service. Configure the agent with an easy human-handoff ("let me have someone call you back") and a strict no-answer policy — one attempt, then it's back to SMS.

The full voice-agent architecture (Retell + n8n + GHL, what breaks in production, testing) is its own guide: How I build production AI voice agents.

What this returns (the math clients care about)

A plumber missing 15 calls/week: even converting 2 of those into jobs at a $300 average ticket = ~$2,400/month recovered, against usage costs measured in tens of dollars (full cost breakdown here). It's the closest thing to found money in local-business automation — which is why every agency now sells it, and why building it correctly (compliance, quiet hours, human handoff) is what separates the setups that last.

Common failure modes

Texting existing customers' routine calls — filter by tag/pipeline stage so your regulars don't get lead-capture texts.
No quiet hours — a 1am "sorry we missed you!" earns spam reports.
Two numbers confusion — textback must come from the number they called. Cross-number replies orphan the conversation.
Set-and-forget — review the conversation log weekly for the first month; you'll rewrite the message twice and it'll be worth it.

I build this exact system — textback through full AI callback — for businesses through Null Studio. Book a call if you want it installed properly, A2P and all.