Compliance and Opt-In Rules

This guide walks you through the key compliance requirements and opt-in rules you need to follow before sending SMS messages in Sender for the first time.

Where to Find This Feature

In the Sender dashboard, go to Account settings → SMS settings.

On this page, you will see the Phone numbers table listing your registered sender IDs with their use case, status, and date added. Below it, the SMS Message Add-ons section displays your Organizational prefix, Opt-out text, and Opt-out link text fields — the core compliance settings that are appended to your SMS messages.

Steps to Set Up SMS Compliance & Opt-In

Before sending any SMS, you must have explicit opt-in consent from each recipient. This means the subscriber actively agreed to receive SMS messages from your business — pre-checked boxes or implied consent do not qualify.

Use Sender’s Forms feature to create signup forms that include a clear SMS opt-in statement, such as “I agree to receive marketing text messages from [Your Business].” Make sure the phone number field captures numbers in international format with the country code (e.g., +1 for the US, +44 for the UK). After publishing the form, subscribers who opt in will appear in your Subscribers list with an Active SMS status.

Step 2 — Configure your opt-out message settings

Go to Account settings → SMS settings and scroll to the SMS Message Add-ons section. You will see three fields:

Organizational prefix — Enter your business or brand name. This text is added to the beginning of every SMS so recipients know who is messaging them.

Opt-out text — Enter opt-out instructions that include the word “STOP,” such as Reply STOP to opt-out. This field is required and must contain “STOP” in the message.

Opt-out link text — Enter unsubscribe link text, such as Unsubscribe: {{unsubscribe_link}}. This provides an additional way for recipients to opt out via a clickable link.

Click Update to save your changes.

Step 3 — Review prohibited content and sender ID compliance

When registering a sender ID in Sender (via Account settings → SMS settings → Add phone number), you will see the TCPA & CTIA compliance notice. This outlines that explicit consent is required before sending SMS to US subscribers and lists content categories that are prohibited on Sender:

S.H.A.F.T. content — Sexual, hateful, alcohol, firearms, or tobacco-related content.

Drugs & vaping — CBD, vaping, cannabis, and related products or content.

Gambling — Betting, lotteries, gaming for money, and related content.

High-risk finance — Loans, debt relief, investments, tax relief, and work-from-home offers.

Ensure your SMS content does not fall into any of these restricted categories. Violations may result in message blocking or account suspension.

Step 4 — Verify subscriber SMS status and phone number format

Go to Subscribers in the left sidebar. Use the SMS status filter at the top of the subscriber list to check the status of your SMS contacts. Available statuses include Active, Bounced, Unsubscribed, Reported spam, and Non-subscribed.

Click on any subscriber to open their profile. You will see separate sections for Email campaign and SMS campaign, each with its own status indicator. Confirm that the subscriber’s phone number is stored with the correct country code prefix (e.g., +370 638 31693) and that their SMS campaign status shows Active before including them in an SMS send.

SMS Compliance Requirements

TCPA (Telephone Consumer Protection Act) — Applies to SMS recipients in the United States. Requires express written consent before sending marketing text messages. Sender displays a TCPA compliance notice during sender ID registration and requires you to confirm that you have obtained subscriber consent.

CTIA (Cellular Telecommunications Industry Association) guidelines — Industry standards enforced by US carriers. CTIA guidelines prohibit certain content categories (S.H.A.F.T., drugs, gambling, high-risk finance) and require that every marketing SMS includes opt-out instructions. Sender enforces these restrictions through its SMS Message Add-ons settings, which require the word “STOP” in your opt-out text.

GDPR (General Data Protection Regulation) — Applies to recipients in the European Union and European Economic Area. Requires a lawful basis (typically explicit consent) for processing personal data, including phone numbers used for SMS marketing. Subscribers must be able to withdraw consent easily at any time.

Sender’s own SMS policies — Sender requires an organizational prefix on every message, a valid opt-out mechanism in every SMS, and prohibits the content categories listed during sender ID registration. These policies apply regardless of the recipient’s location and are enforced through the SMS Message Add-ons configuration on the SMS settings page.

Always consult a legal professional for advice specific to your jurisdiction and use case. The information above is general guidance and does not constitute legal advice.

What Happens Next

After configuring your compliance settings, send a test SMS to your own phone number to verify that the organizational prefix, message content, and opt-out text all display correctly.

You can manage your opt-out text and organizational prefix at any time by returning to Account settings → SMS settings and updating the SMS Message Add-ons section.

Subscribers who reply “STOP” will automatically have their SMS status changed to Unsubscribed, which you can monitor using the SMS status filter on the Subscribers page.

With your compliance settings in place, you are ready to create and send SMS campaigns from the SMS campaigns section in the left sidebar.

Common Issues

Opt-out text rejected → The Opt-out text field requires the word “STOP” to be included in the message. If your text is rejected, check that it contains “STOP” (e.g., Reply STOP to opt-out) and click Update to save.

Subscriber SMS status shows Non-subscribed → This means the subscriber does not have a valid phone number on their profile or has not opted in to SMS. Open the subscriber’s profile, add a phone number in international format with the country code, and confirm their SMS consent.

Sender ID status shows In Progress → After registering a new sender ID, it may take time for carrier verification to complete. The status will update to Active once approved. Do not send campaigns until the status changes from In Progress.

Prohibited content blocking → If your SMS messages are blocked, review your content against the restricted categories (S.H.A.F.T., drugs, gambling, high-risk finance). Remove any prohibited content and resubmit your message.

Phone number format errors → Phone numbers must include the full country code prefix in international format (e.g., +1 for the US, +44 for the UK). If subscribers are not receiving messages, verify their phone numbers include the correct country code on their subscriber profile.

FAQs

What is a sender ID?

A sender ID is the name or phone number that appears as the sender when recipients receive your SMS. In Sender, you can choose between a Toll-free number (a +18xx format phone number available in the US and Canada) or an Alphanumeric ID (your brand name, available outside the US and Canada, one-way messaging only). You select your sender type when clicking Add phone number on the SMS settings page.

Do I need consent to send SMS messages?

Yes. SMS regulations like TCPA (US) and GDPR (EU) require explicit consent from recipients before sending marketing SMS. Collect consent through signup forms with a clear opt-in statement. Sender displays a compliance notice during sender ID setup as a reminder. Consult a legal professional for guidance specific to your jurisdiction.

What should I include in every SMS message for compliance?

Every marketing SMS should include your business name (set via the Organizational prefix field) and opt-out instructions containing the word “STOP,” such as “Reply STOP to opt-out.” These are configured in the SMS Message Add-ons section under Account settings → SMS settings. Sender appends these automatically to your messages.

What phone number format does Sender require?

Phone numbers must be stored in international format with the country code prefix (e.g., +1 for the United States, +44 for the United Kingdom). You can verify the format on each subscriber’s profile under the SMS campaign section, which displays the phone number with a country flag indicator.

How do I check a subscriber’s SMS opt-in status?

Go to Subscribers and use the SMS status filter dropdown at the top of the list. You can filter by Active, Bounced, Unsubscribed, Reported spam, or Non-subscribed. Only subscribers with an Active SMS status should receive your marketing SMS messages.

What content is prohibited in SMS messages sent through Sender?

Sender prohibits S.H.A.F.T. content (sexual, hateful, alcohol, firearms, tobacco), drugs and vaping products, gambling-related content, and high-risk finance content (loans, debt relief, investments, tax relief, work-from-home offers). These restrictions are displayed during sender ID registration and align with CTIA carrier guidelines.

Are there SMS sending restrictions by country?

Yes. Some countries have specific carrier restrictions on sender IDs, content, or sending hours. For example, Toll-free numbers are only available in the US and Canada, while Alphanumeric IDs are available outside those countries. Check Sender’s SMS documentation or contact support for details about restrictions in your target countries.