Two-Way SMS in HighLevel

Updated: February 6, 2026  | 
Author: Bill Stilwell

This post covers how Two-Way SMS works in HighLevel, what LC Phone is, how to provision a number, the A2P 10DLC registration requirement, how automated SMS and reply detection work, compliance handling, and how SMS integrates with the CRM and conversations inbox.

Reading time: about 7 minutes.

What Is Two-Way SMS in HighLevel?

Two-Way SMS in HighLevel means the business can both send text messages to contacts and receive text message replies – all through a dedicated business phone number managed within the HighLevel platform.

This is distinct from one-way SMS blasting, where messages go out but replies are not handled. Two-way SMS enables real conversations – a lead texts back, the team (or an AI) responds, the relationship develops through a channel most people check within minutes.

Every SMS conversation – automated and manual – is stored in the HighLevel Conversations Inbox and linked to the contact’s CRM record. The SMS thread with a lead is part of their complete relationship history alongside emails, calls, and form submissions.

LC Phone – HighLevel’s Native Telephony

LC Phone (LeadConnector Phone) is HighLevel’s native telephony layer. It provides the phone numbers, SMS infrastructure, and voice call capabilities used within HighLevel sub-accounts.

SMS in HighLevel runs on LC Phone – provisioning a number through HighLevel means provisioning an LC Phone number.

LC Phone numbers support SMS, MMS, and voice calls from the same number. A lead who texts the number is in the SMS inbox.

A lead who calls the same number reaches the call handling configuration for that sub-account. The number is a unified communication identifier, not a SMS-only tool.

Usage costs for LC Phone – per-message SMS costs, per-minute call costs – are what the Rebilling feature passes to clients. LC Phone is the usage layer that generates those costs.

Provisioning a Phone Number

Phone numbers are provisioned in the sub-account at Settings, then Phone Numbers. Click Add Phone Number, select the number type, choose the area code or region, and provision.

The number is assigned immediately and ready for use.

Number types available: local 10-digit numbers (most common for small businesses – they look like a standard local phone number to recipients), toll-free numbers (good for national businesses or for separating marketing lines), and short codes (5 or 6-digit numbers designed for high-volume campaigns – require separate registration and approval, used for enterprise-scale SMS).

For most HighLevel users, a local 10-digit number in the business’s local area code is the right starting point. Recipients recognize the local area code, which improves answer rates for calls and open rates for SMS compared to unrecognized out-of-area numbers.

SMS in the Conversations Inbox

All SMS – inbound and outbound – appears in the Conversations Inbox with the SMS channel indicator. The full SMS thread with each contact is visible in one continuous conversation view, with timestamps and direction indicators for each message.

Sending an SMS from the inbox is straightforward: open the contact’s conversation, confirm SMS is selected as the channel, type the message, send. The reply from the contact arrives in the same conversation thread – the back-and-forth is organized as a dialogue rather than isolated events.

The contact’s SMS history is also visible on their contact record in the activity timeline – every message sent and received, in order, with the same timestamps as the conversation inbox view.

Automated SMS via Workflow Builder

The most common use of Two-Way SMS in HighLevel is not manual messaging – it is automated messaging through Workflow Builder. A workflow fires an SMS action when a trigger event occurs: form submitted, contact created, appointment booked, pipeline stage changed, tag added.

Automated SMS workflows power lead follow-up sequences. When a lead submits a form, the workflow fires within seconds – sending the lead an SMS confirming receipt and setting expectations for next steps.

At the same time or a moment later, the workflow sends an SMS notification to the sales rep with the lead’s name and phone number.

Follow-up sequences continue automatically. Day 1, Day 3, Day 7 SMS messages go out at the configured intervals without any manual action.

Each message uses the contact’s name as a merge field so the messages feel personal even though they are automated.

Reply Detection and Workflow Branching

One of the most powerful elements of HighLevel’s Two-Way SMS is the ability to detect when a contact replies to an SMS and take action based on that reply. Workflow Builder supports this through the “Customer Replied” trigger and conditional branching on reply content.

When an automated follow-up sequence is running and a contact replies with anything – “yes,” “call me,” “interested,” “stop” – the workflow can detect that reply and change course. A contact who replies “Yes, I’m interested” triggers a different path than a contact who replies “Not now” – and both differ from a contact who does not reply at all.

Practically: when a reply is detected, the workflow removes the contact from the automated sequence (so they do not continue receiving the Day 3 and Day 7 messages) and notifies the sales team that an engaged lead is waiting for a personal response. The team member receives an SMS notification: “Lead [Name] just replied to your follow-up.

Call them now.”

MMS – Picture and Media Messages

HighLevel supports MMS in addition to SMS. MMS messages can include images, videos, audio files, and other media.

They cost slightly more per message than standard SMS but add significant value for use cases where a visual element matters.

Home services businesses send before-and-after photos of completed work in follow-up messages. Real estate agents send property photos or virtual tour links.

Restaurants send menu photos or specials images. The visual element makes the message more engaging and more memorable than text alone.

MMS is sent from the Conversations Inbox by attaching a media file to a message before sending. In workflow SMS actions, MMS is configured by adding a media URL to the action settings.

Personalization in SMS Messages

HighLevel SMS messages support merge fields – inserting contact-specific data into the message text. The most common use is inserting the contact’s first name: “Hi {{contact.first_name}}, thanks for your inquiry…” sends as “Hi Sarah, thanks for your inquiry…” to Sarah.

Custom field values are also available as merge tags. An SMS to a lead who inquired about a specific service can reference their service interest: “Hi {{contact.first_name}}, following up on your interest in {{contact.service_interest}}…” The personalization makes automated messages feel less automated – and personalized messages consistently outperform generic ones for reply rates.

Compliance – STOP, DND, and A2P 10DLC

SMS compliance in the United States involves two distinct requirements.

The first is opt-out handling. When a contact replies STOP to any SMS from an LC Phone number, HighLevel automatically marks that contact’s SMS DND as active – preventing any further automated SMS from being sent to that number.

This is a carrier-level requirement and HighLevel handles it automatically without any manual action from the agency or business.

The second is A2P 10DLC registration. The US carrier ecosystem requires businesses that send application-to-person (A2P) SMS messages from 10-digit long code (10DLC) numbers to register their brand and messaging campaigns.

Without this registration, SMS messages from local HighLevel numbers face increased filtering and blocking by carriers – significantly reducing deliverability.

A2P registration is completed in HighLevel through a guided process: register the business brand with the campaign registry, then register the specific messaging campaign (what the SMS messages are about). Approval typically takes several business days.

Starting this process early – before the sub-account needs to send SMS at any volume – prevents deliverability problems.

Character Limits and Segments

Standard SMS messages have a 160-character limit per segment. Messages longer than 160 characters are automatically split into multiple segments and sent as concatenated SMS – the recipient’s phone displays them as one message, but each segment is billed separately for LC Phone usage.

Unicode characters (emoji, accented characters, some special symbols) reduce the per-segment limit to 70 characters. Avoid emoji in high-volume automated SMS unless the personalization value is worth the added cost from shorter segments.

For most conversational and follow-up SMS messages, staying under 160 characters is practical and cost-effective. Reserve longer messages for cases where the additional context genuinely improves the response rate.

What Can You Do With It?

• Follow up with new leads within seconds of form submission: An automated SMS fires within seconds of a new contact creation – confirming the inquiry, setting expectations, and starting the follow-up sequence before the lead has moved on to the next tab.
• Receive and respond to lead replies from the unified inbox: When a lead texts back, the reply appears in the Conversations Inbox alongside all other channels. The team responds from the same interface they use for email and Facebook messages.
• Build automated nurture sequences that feel personal: Multi-message SMS sequences with personalization merge fields deliver the right message at the right time without manual effort – consistently, to every lead, regardless of volume.
• Detect when a lead is ready and alert the team immediately: Reply detection in workflows identifies when a lead responds to any automated message and triggers an immediate team notification – so a human follows up while the lead is engaged.
• Send appointment reminders, confirmations, and review requests: Every operational SMS – confirmations, reminders, follow-ups, review requests – is automated through workflows rather than manual sending. The business communicates consistently without anyone sending individual messages.

Key Definitions

Use Cases by Industry

Home Services – 5-Minute Lead Response

A roofing company runs Google ads that drive leads to a HighLevel form. When the form is submitted, a workflow fires two simultaneous SMS messages: one to the owner (“New lead: [Name], [Phone] – submitted roof inspection request”) and one to the lead (“Hi [First Name], thanks for requesting a roof inspection!

We’ll call you within the next 5 minutes. – [Owner Name], ABC Roofing”).

The lead gets a personal, named confirmation within 30 seconds of submitting. The owner gets a direct notification with the lead’s phone number.

If the owner calls within 5 minutes, they reach a lead who just received a text from the business and is actively expecting the call.

Result: The 5-minute response window – consistently shown to significantly improve lead-to-appointment conversion – is operationally achievable because the automation fires instantly and the owner’s notification includes everything needed to make the call.

Medical Practice – Appointment Reminders

A dental practice automates appointment reminders through HighLevel Two-Way SMS.

48 hours before: “Hi [First Name], your appointment is in 2 days. Reply CONFIRM or CANCEL.” 24 hours before: “Reminder: your appointment is tomorrow. Reply CONFIRM if you’re still coming.”

Reply detection handles the responses automatically. CONFIRM replies update the contact’s tag and remove them from further reminders.

CANCEL replies trigger a workflow that notifies the front desk and opens a rebooking sequence. No-reply contacts receive a final day-of reminder.

Result: No-show rates decrease because reminders are consistent and response-enabled. Cancellations are caught 24 hours in advance rather than as day-of no-shows – giving the practice time to fill the slot. The entire reminder system runs without any staff involvement.

Real Estate – Active Buyer Engagement

A real estate agent uses Two-Way SMS to stay in contact with active buyers throughout a search process that spans weeks or months. When a new listing matches a buyer’s saved criteria, the agent sends a personalized MMS: a photo of the property with a short message about why it matches the buyer’s criteria.

The buyer texts back with reactions – “Love it, can we see it?” or “Not quite right, too small.” Each reply opens a conversation in HighLevel that the agent responds to personally. The two-way nature of the channel makes the buyer feel like the agent is paying personal attention to their search – rather than sending generic property alerts.

Result: Active buyers engage more frequently and more personally through SMS than through email. The agent closes sales faster because communication is more timely and personal – property reactions and availability discussions happen in near-real-time rather than over slow email exchanges.

Restaurant – Review Request and Feedback Loop

A restaurant uses a HighLevel form at checkout to collect customer phone numbers. After a visit, an automated SMS fires: “Hi [First Name], thanks for dining with us at [Restaurant]!

How was your experience? Reply GREAT, GOOD, or MEH.” The restaurant collects real-time feedback via SMS.

GREAT replies trigger a follow-up: “Glad you enjoyed it! Would you mind leaving us a review? [Google Review Link].”

GOOD and MEH replies trigger a different path: a personal follow-up from the manager with a discount offer and an apology for any shortfall.

Result: The restaurant captures feedback immediately after the visit when impressions are fresh. Satisfied customers are guided to leave public reviews. Dissatisfied customers are intercepted with a personal response before they post a negative review. The entire system runs automatically without any manual monitoring.

Who Is This For?

How to Set Up and Use Two-Way SMS

Step 1: Provision a phone number

Go to Settings, then Phone Numbers. Click Add Phone Number.

Select a local number in the desired area code. Provision the number.

Step 2: Complete A2P 10DLC registration

Navigate to the A2P registration section in Settings. Submit the business brand registration.

Once approved, register the SMS campaign(s) – what the messages are about. Do not skip this step for US numbers.

Step 3: Send a test SMS

Go to Conversations, find a contact with your own phone number, open the conversation, select SMS channel, and send a test. Verify receipt on your phone.

Reply and confirm the reply appears in HighLevel.

Step 4: Configure inbound SMS notifications

In Settings, then Notifications, set up alerts for new inbound messages so the team is notified when leads reply.

Step 5: Build the lead notification workflow

In Workflow Builder, create a workflow triggered by contact creation or form submission. Add an SMS action notifying the owner or sales rep with the lead’s name and phone number.

Step 6: Build the lead follow-up sequence

Add SMS actions to the workflow for Day 0 (immediate), Day 1, Day 3, and Day 7. Use merge fields for the contact’s first name.

Keep messages short – under 160 characters.

Step 7: Add reply detection

Add a Customer Replied branch in the workflow. When a reply is detected, remove the contact from the automated sequence and notify the team for a personal follow-up.

Step 8: Test the full workflow

Submit a test form with your personal phone number. Follow the automated sequence – receive messages, reply, confirm the reply detection fires correctly and the team notification arrives.

Step 9: Monitor via mobile app

Install the HighLevel Mobile App and enable push notifications for new SMS. The notification ensures inbound replies are seen promptly from any location.

How Does It Connect to HighLevel?

• Conversations Inbox: Every SMS – automated and manual, inbound and outbound – appears in the Conversations Inbox. The inbox is where the team monitors and responds to all SMS alongside email and other channels.
• SMS Marketing Automation: Two-Way SMS is the technical foundation for SMS Marketing Automation. The automated sequences, campaign sends, and bulk messaging features all rely on the LC Phone infrastructure that Two-Way SMS uses.
• Workflow Builder: Workflow Builder is where automated SMS actions are configured. Every trigger-to-SMS-action connection – form submission to follow-up sequence, reply detection to team notification – is built in workflows.
• Appointment Reminders: Appointment reminders are one of the highest-value automated SMS use cases. The reminder workflow sends confirmation, reminder, and post-appointment messages – all through the same Two-Way SMS infrastructure with full reply handling.
• Rebilling: LC Phone SMS usage costs are what Rebilling passes to clients. Each SMS segment sent generates a usage cost. For agencies managing high-volume SMS for clients, Rebilling connects the SMS usage directly to client billing.

Common Questions

What is Two-Way SMS in HighLevel?

The ability to send and receive text messages from a dedicated HighLevel LC Phone number – with full conversation history in the Conversations Inbox, automated workflow integration, and CRM contact linking.

What is LC Phone in HighLevel?

HighLevel’s native telephony infrastructure. Provides the phone numbers, SMS, MMS, and voice call capabilities for HighLevel sub-accounts.

How do I get a phone number for SMS in HighLevel?

Settings, then Phone Numbers. Click Add Phone Number, choose the number type (local, toll-free), select the area code, and provision.

Can I receive replies to automated SMS messages in HighLevel?

Yes. Replies appear in the Conversations Inbox and fire the Customer Replied workflow trigger – enabling automated branching based on whether and what a contact replies.

How does SMS opt-out (STOP) work in HighLevel?

STOP replies automatically set the contact’s SMS DND. Automated workflows no longer send SMS to DND contacts.

Handled automatically by HighLevel – no manual action required.

Can I send MMS (picture messages) through HighLevel?

Yes. Attach images or media in the Conversations Inbox compose area or configure a media URL in a workflow SMS action. MMS costs slightly more per message than standard SMS.

What is A2P 10DLC registration and why does it matter for HighLevel SMS?

US carrier registration required for businesses sending SMS from local 10-digit numbers. Without it, messages face increased filtering and blocking.

Required for reliable delivery. Complete through HighLevel’s A2P registration process in Settings.

Can multiple team members receive SMS messages in HighLevel?

Yes. All sub-account users can see the inbox.

Conversation assignment designates responsibility. Notifications route alerts to specific users.

Workflows send personal SMS notifications to specific team members’ phones.

Is there a character limit for SMS messages in HighLevel?

160 characters per segment. Messages longer than 160 characters are split into multiple segments – each billed separately.

Unicode characters (emoji) reduce the limit to 70 characters per segment.

Can I use personal merge fields in HighLevel SMS messages?

Yes. Insert contact field merge tags – first name, custom fields – into any SMS message using the merge field selector in the compose area or workflow action.

To Wrap It Up

SMS is the most reliably opened communication channel available. The open rate for SMS consistently far exceeds email – not because SMS is better written, but because people treat text messages as personal and time-sensitive in a way they do not treat email.

A new text message gets attention. A new email joins a queue.

HighLevel’s Two-Way SMS capitalizes on this by making SMS the primary channel for time-sensitive lead follow-up and operational communication – and by making the two-way nature of it genuinely useful through reply detection and automated branching. The combination of automated outreach and automated reply detection means leads who are ready to engage are identified and escalated to a human immediately, while leads who are not ready continue in the automated sequence without any manual management.

The compliance pieces – A2P registration and opt-out handling – are not optional details. SMS deliverability in the US depends on proper A2P registration.

An unregistered sub-account sending SMS at any volume will encounter filtering problems that undermine the entire communication strategy. Do the registration early, before it becomes a problem.

Here is how to get started:

1. Go to Settings, then Phone Numbers and provision a local number in the appropriate area code
2. Navigate to A2P registration in Settings and complete the brand and campaign registration
3. Send a test SMS from the Conversations Inbox to verify the number is working
4. Build the lead notification workflow – SMS alert to owner on new contact creation
5. Build the lead follow-up sequence – Day 0, Day 1, Day 3, Day 7 with personalization
6. Add reply detection branching – team notification when a lead responds
7. Test the complete workflow with a personal phone number as the test contact
8. Enable mobile push notifications for new SMS in the HighLevel Mobile App

Complete A2P 10DLC registration before sending any meaningful volume of SMS. The registration process takes several business days – start it when the sub-account is first configured, not after the first SMS campaign has already failed to deliver.

Carrier filtering for unregistered numbers is aggressive and getting worse over time as the carriers enforce registration requirements more strictly.