SMS Double Opt-In Overview

Using SMS as a marketing channel requires compliance with various regulations and best practices. One of the most important SMS compliance practices is obtaining users' consent to receive SMS marketing. SMS Double Opt-In is an automated opt-in flow for Iterable SMS channels that asks users to confirm their subscription in order to receive SMS messages from your brand.

Benefits of using SMS Double Opt-In include:

• No complicated journey setup.
• Time saved with pre-built confirmation and legal disclaimer messages.
• A digital record of opt-in consent, supporting compliance and building trust.
• Improved data quality with real phone numbers confirmed by engaged users.

This article explains how SMS Double Opt-In works, when to use it, and how to set it up in Iterable.

# In this article

# How it works

There are two ways to subscribe users to a double opt-in message type:

• With a custom web form that triggers the double opt-in API. This option requires some web development.

• With Smart Opt-In, which uses an email or in-app campaign to trigger the double opt-in. This option requires setting up a Smart Opt-In link and adding it to an email or in-app campaign.

# Using a web form to trigger the double opt-in flow

When a user requests to subscribe to a double opt-in message type, Iterable sends a SMS to their phone number asking for confirmation. To finish subscribing to the message type, the user must reply via SMS. If the user doesn't reply, they won't receive SMS messages from your brand.

Here's how it works:

1. First, the user completes a web form and selects to receive SMS messages from your brand. The form can include multiple message types that the user can subscribe to.

2. Iterable sends a confirmation message to the user's phone number. Iterable's default message that includes the brand name, messaging initiative (a description of the content associated with the given message type), and a link to the SMS disclaimer.

3. The user must reply to the message to confirm their subscription.

4. Iterable sends a legal disclaimer message to the user's phone number.

5. The user's subscription status changes to subscribed in Iterable and they're now eligible to receive SMS campaigns from message type(s) they selected in the form.

# Using Smart Opt-In with a double opt-in message type

When you use SMS Smart Opt-In to enroll users to a double opt-in message type, Iterable does not follow the same flow as the web form. Instead, the user confirms their subscription by sending a message from their phone's messaging app.

Here's how it works:

1. First, create and send an email or in-app campaign with a Smart Opt-In link included in the message.

2. When a user clicks the Smart Opt-In link, their phone's messaging app opens with a pre-filled SMS message to confirm their subscription.

3. The user sends the message to complete the double opt-in process.

4. Iterable sends a legal disclaimer message to the user's phone number that also confirms their subscription.

To learn more about Smart Opt-In, read Smart Opt-In Overview.

# When to use SMS Double Opt-In

Double opt-in is a valuable choice when you want to ensure that users have confirmed their intent to receive SMS messages from your brand. It is particularly important when sending marketing messages that require a call to action, such as making a purchase or signing up for a service.

In the US, double opt-in is mandatory for abandoned shopping cart campaigns.

Implementing double opt-in adds an extra step where recipients confirm their consent on their handset. While this may seem like an inconvenience, it offers several benefits, like: reduced data collection of incorrect numbers, a complete digital record of consent, reduced likelihood of complaints, prevention of malicious activity, and building trust with your audience.

# Components of the SMS Double Opt-In flow

The SMS Double Opt-In flow has several components that work together to confirm a user's subscription to a message type. To learn more about each piece of the flow and how they work, read SMS Double Opt-In Components.

# Setting up SMS Double Opt-In

Using SMS Double Opt-In requires setting up a double opt-in message type and either a web form or Smart Opt-In link to trigger the double opt-in flow. To learn more about building the SMS Double Opt-In flow, read Setting up SMS Double Opt-In.

# Subscribing users to double opt-in message types

A user can subscribe to a SMS double opt-in message type in one of two ways:

• Providing their phone number and submitting your form, then replying Y to a confirmation request.
• Clicking a Smart Opt-In link in an email or in-app campaign from a mobile phone, and then sending the pre-filled SMS message to your SMS sender to confirm their subscription.

If the user doesn't reply to the confirmation with Y or send the pre-filled SMS message, they remain unsubscribed and don't receive campaigns with the associated double opt-in message type.

# Viewing user subscriptions to double opt-in message types

To view the subscription status of a user to a double opt-in message type, you can use the User profile page or segmentation.

# Viewing a user's subscription status in the user profile page

To view the subscription status for a particular user, visit the user's profile page in Iterable and go to the Subscriptions area.

Double opt-in message types can have any of these statuses:

• No — The user has not subscribed to the message type.

• Pending — The user has requested to subscribe to the message type but hasn't confirmed their subscription yet.

• Yes — The user has confirmed their subscription and is subscribed to the message type.

# Viewing a user's subscription status in segmentation

Use segmentation to filter users based on their event history and the unique properties of events related to the SMS Double Opt-In flow.

For example, SMS send events are recorded in the user's profile history with a unique property, doubleOptInMessage, that contains the text of the message sent.

You can also create a segmentation query to filter users based on SMS send events for the SMS Double Opt-In confirmation and disclaimer campaigns.

(At this time, Iterable can't use the segmentation tool to filter users based on their subscription status to double opt-in message types.)

# Unsubscribing users from double opt-in message types

The double opt-in message type processes user opt-outs in the same way as other message types. To learn more, read SMS Unsubscribes and Resubscribes.

# FAQs

# Can I customize the confirmation and disclaimer messages?

You can customize certain parts of the confirmation and disclaimer messages. Ways to customize the confirmation message:

• Brand name
• Messaging initiative
• SMS disclaimer link

# What happens if a user doesn't reply to the confirmation message?

Users who have not yet replied to the confirmation message don't receive SMS messages from the double opt-in message type.

For compliance reasons, you shouldn't re-trigger a double opt-in confirmation if the user hasn't confirmed their intent to opt-in. Another confirmation message can be triggered via the user resubmitting the form.

# Do automated double opt-in messages count towards my SMS usage?

Yes, the confirmation and disclaimer messages count towards your SMS usage, and usage varies for each individual user depending on the length of the messages.

When you use a web form, the SMS Double Opt-In flow sends two outbound SMS messages to the user (confirmation and disclaimer), and one inbound SMS message from the user (confirmation).

When you use Smart Opt-In, Iterable sends one message to the user (legal disclaimer). The user replies with one message back to confirm their subscription.

The total segment count for each of these messages varies.

# How many SMS segments do the automated double opt-in messages use?

Iterable does not limit the overall character count of the double opt-in confirmation and legal disclaimers to one segment. As with all SMS campaigns, SMS segments are determined by the character encoding and overall character length of a given message. To learn more about SMS segments, read Creating SMS Templates.

Factors that impact the character count of the double opt-in messages include:

• Character length of the brand name, messaging initiative, and SMS disclaimer links.

  The character length changes to reflect the length of the fields you input when you create your double opt-in message type: the brand name, messaging initiative, and SMS disclaimer link. Keeping the length of these fields to a minimum can help keep the message within the 160-character limit for one SMS segment.

• Number of message types in a single subscription request.

  If you have multiple message types in a single subscription request, the brand names and messaging initiatives are concatenated in the confirmation message. This can increase the character count and quickly exceed one SMS segment.

• Append opt-out language.

  The character count can also change depending on the length of your opt-out language and whether your SMS opt-out language is appended. These are settings that you can sometimes customize and vary by country. To learn more, read Customizing SMS Opt-Out Instructions.

# Can I create transactional messages with a double opt-in subscription policy?

Yes, you can use SMS Double Opt-In for transactional and marketing messages.

# Can I use the SMS Double Opt-In flow for other channels?

No, the double opt-in subscription policy is unique to SMS channels in Iterable.

# Can I use a journey to subscribe users to double opt-in message types?

Partially. Double opt-in confirmation messages and legal disclaimers are not triggered when subscribing to a double opt-in message type via journey tiles, and is generally not a recommended best practice.

# How does the SMS Double Opt-In flow work when a project has Frequency Management enabled?

When a project has Frequency Management enabled, the SMS Double Opt-In flow still works as expected. The user receives the confirmation and disclaimer messages regardless of message frequency settings. SMS Double Opt-In messages aren't subject to Frequency Management settings.

# Can I use double opt-in message types with other Subscriptions API endpoints?

To trigger the SMS Double Opt-In flow, you must use the double opt-in API endpoint:

POST /api/subscriptions/subscribeToDoubleOptIn

However, double opt-in message types are backwards-compatible with other Subscriptions API endpoints. This means that users who subscribe to a double opt-in message type via other API endpoints don't receive the confirmation and disclaimer messages from the SMS Double Opt-In flow and are considered subscribed immediately.