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Overview

SMS is a scalable channel for reaching users in real-time, even outside your app or website. It boasts some of the highest open and engagement rates of all messaging channels.

SMS channel setup overview

Before sending SMS or MMS messages, make sure you:

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SMS setup

In your OneSignal dashboard, navigate to Settings > SMS > Set up SMS.

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Select provider

You can send SMS using either OneSignal-managed infrastructure or your own Twilio account.

SMS provider selection options


  • OneSignal
  • Twilio
OneSignal leverages Twilio under the hood. Choose this if:
  • You send more than 5,000 SMS per month
  • You are on a paid OneSignal plan (see pricing)
Click Book Demo with SMS Expert to get assistance from our team.
While waiting for verification, you can begin Designing SMS & MMS templates and ensuring you meet the SMS registration requirements.

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Set default “From” number

Once verified, OneSignal will retrieve all Twilio phone numbers linked to your account. Select a default number to use when sending. You can override this later during message creation.

Setting a default phone number

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Send a test SMS

Enter your phone number and click Send Test SMS. If the message doesn’t arrive:
  • Confirm the default number supports SMS
  • Check Twilio logs for errors
Twilio trial accounts require recipient numbers to be pre-registered.
Click Next: Add Subscribers.

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Understanding users and subscriptions

Each unique phone number is treated as a separate SMS subscription in OneSignal. Subscriptions can be created by:
  • Uploading phone numbers via CSV
  • Using the API
  • Capturing numbers with a web prompt
  • Using the SDK’s addSms method
Refer to SMS Opt-in and Collection for implementation details. Important:
  • Use E.164 format for phone numbers
  • Phone numbers are considered anonymous until you assign them an External ID.

Users

Manage users, assign External IDs, and track activity.

Subscriptions

Learn how subscriptions work across devices.

Segments

Target users based on behavior and traits.

Upload CSV

Bulk upload phone numbers to create subscribers.

Create User/Subscription APIs

Use APIs to manage SMS users.

Web Prompt

Prompt users to input their phone number.

SMS SDK Methods

Programmatically add or remove SMS subscribers.

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Design SMS & MMS

Great SMS/MMS messages are concise, personalized, and cost-effective. Each message is charged per segment.
Pricing is based on message segments, which depend on character count and encoding type. If your message exceeds segment limits, it may be split and billed as multiple messages.Use OneSignal’s built-in character estimation to preview segment count and manage cost.

SMS overview

Learn how SMS/MMS design, content, and delivery works.

Templates

Save time with reusable message templates.

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Message personalization and localization

Make your messages more relevant by customizing based on user data and language preferences.
Personalization increases character count and can cause messages to split into multiple segments. Always test before sending to large audiences.

Message Personalization

Use dynamic variables like name or location.

Multi-Language Messaging

Automatically send messages in users’ preferred language.

Dynamic Content

Tailor messages in real-time based on user data.

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Compliance and registration requirements

SMS and RCS messages are heavily regulated and require specific compliance and registration requirements. For example, with the launch of iOS 26, SMS messages from “unknown” senders will be screened out. You can become a “known” sender by using sign-up methods that prompt users to send the first message like:
  • Text-to-join keywords
  • Tap-to-join links that open your customer’s texting app with pre-filled keywords.
  • QR codes that open your customers’ texting app with a pre-filled keyword that starts the text thread.
With these opt in methods, Apple will automatically consider the brand a known sender.

SMS Regulatory Compliance

Understand and follow applicable laws.

SMS Registration Requirements

Ensure your opt-in process meets standards.

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Senders

Manage your From phone numbers under Settings > SMS > Senders. Here, you can:
  • Update your default sender
  • Choose whether the number can receive replies
Use built-in and custom keywords for managing user consent:
  • Double opt-in confirmation
  • Opt-out requests (e.g., "STOP")
  • Re-subscription (e.g., "START")
  • Help inquiries
Auto-responders allow you to send automated replies based on keywords.

SMS consent keyword management

Configure default consent keywords.

SMS keywords

Set up custom auto-response keywords.

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Analytics and troubleshooting

Monitor performance and troubleshoot delivery:

SMS message reports

View delivery and engagement metrics.

Analytics overview

Explore multi-channel engagement analytics.

SMS FAQ

Common troubleshooting steps.
Congratulations! Your SMS setup is complete.Next steps:
  • Journeys: Build automated messaging flows
  • Tags: Add user-level data for targeting
  • Analytics: Track engagement and conversion metrics
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