--- title: "Transactional Journeys: SMS" slug: "transactional-journeys-sms" updated: 2026-01-27T10:52:16Z published: 2026-01-27T10:52:16Z canonical: "academy.insiderone.com/transactional-journeys-sms" --- > ## Documentation Index > Fetch the complete documentation index at: https://academy.insiderone.com/llms.txt > Use this file to discover all available pages before exploring further. # Transactional Journeys: SMS > **Suggested readings:** [Transactional Journeys](/v1/docs/transactional-journeys), [Dynamic Content in Transactional Journeys](/v1/docs/dynamic-content-in-transactional-journeys), [Transactional SMS Channel Analytics](/v1/docs/transactional-journeys-sms-channel-analytics) SMS Channel allows you to send real-time transactional text messages to users who enter a journey through an On API Call starter. Transactional SMS is designed for time-sensitive, informational messages such as one-time passwords, order updates, delivery notifications, and account-related alerts. Messages are sent immediately when a user reaches the SMS element in the journey. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-113526.png) When you must deliver the messages immediately, content is operational or informational, users expect a message as part of a system action, or delivery speed is critical, you can use Transactional SMS. It is not designed for promotional or engagement-driven use cases. In Transactional Journeys, SMS messages are sent as a single, immediate operation. When a user reaches the SMS element: - The message is generated using the configured text and dynamic content - The SMS is sent immediately - The journey continues without waiting for user interaction > [!NOTE] > Each user receives an individual SMS message. Messages are **not** **batched** or **scheduled**. > > Transactional SMS does **not** **evaluate** user **consent**, **opt-in** status, or **silent hours** before sending. ## Step 1: Add an SMS Element on the canvas To send an SMS message in a transactional journey, add an SMS element from the channel list on the canvas. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-113806.png) ## Step 2: Configure message text The Message Text field is where you define the SMS content that will be sent to users. You can type plain text, insert dynamic content, and include URLs. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-113927.png) > [!WARNING] > Transactional SMS does **not** **automatically** append any **unsubscribe** sentence or **opt-out** text. ## Step 3: Select dynamic content Dynamic content allows you to personalize SMS messages using data sent with the API request that triggers the journey. Dynamic content in SMS: - Uses only dynamic attributes whitelisted on the [On API Call starter](/v1/docs/on-api-call-starter). - Does **not** **support** CDP attributes, event parameters, coupons, recommendations, or product catalog items. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-114053.png) > [!WARNING] > If a dynamic attribute is **not** **whitelisted** on the starter, it **cannot** **be** **used** in the SMS content. ## Step 4: Character count and message parts SMS message parts are calculated based on **character** **count**. Dynamic content **placeholders** do **not** **increase** the character **count**. **Fallback** values for dynamic content are **included** in the character **count**. Messages longer than the standard limit are **split** into **multiple** SMS parts. > [!NOTE] > Because Transactional SMS does **not** **include** an **unsubscribe** sentence, character count reflects only the message text and links you configure. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-114601.png) You can view detailed character and message part information under Message Details. This section shows: - Total character count - Number of SMS parts that will be sent - Impact of links and fallback values ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-1768898215915.png) ## Step 5: Enable Short URLs You can enable Short URLs for links included in your SMS content. When Short URLs are enabled: - Long URLs are automatically shortened. - Link click tracking is enabled. - Character usage is reduced. Short URLs are **recommended** for transactional messages that include **links**. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-115256.png) ## Step 6: Configure UTM Parameters You can enable UTM Parameters for links in your SMS message to **automatically** **append** them to the URLs and track **clicks** in **external** **analytics** tools. UTM parameters are applied only to **URLs** **inside** the SMS content. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-115342.png) ## Step 7: Preview The **Preview** section lets you see how your SMS message will appear on a mobile device. A preview shows the message **text**, dynamic content **placeholders**, **links**, and **shortened** **URLs**. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-115532.png) ## Step 8: Preview and test message [Preview and Test Message](/v1/docs/transactional-journeys-preview-and-test-message) let you render the SMS message with real dynamic content values and send a test SMS to a phone number. You can preview dynamic content values entered **manually** or click the **Use Random Values** button for **randomly** generated values. Dynamic content values used in preview and test messages are for **testing** **purposes** only and do not reflect real user data. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-115909.png) This process does **not** **require** a real user journey entry, but uses dynamic content values for testing purposes to validate personalization before activating the journey. You can: - Preview with **empty** dynamic content. - Preview with **randomly** generated values. - Preview with **manually** entered values. - Send the test messages **immediately**. - Send test emails to **up to 5** phone numbers. ![](https://cdn.document360.io/c6df4583-da94-4cb2-bb8a-be0cbdd11109/Images/Documentation/image-20251230-120237.png) ## Step 9: Save the SMS element After configuring the SMS content and settings, click the **Save** button to apply the changes. SMS elements do **not** **auto-save**. Unsaved changes are lost if you leave the page. ## Limitations of Transactional SMS The following capabilities are not supported: - **Unsubscription sentences**, because transactional use cases bypass opt-in checks and do not include opt-out mechanisms within message content. - **Silent hours**, as transactional messages are time-critical and must be delivered immediately when triggered. - **Send Time Optimization**, since delaying delivery conflicts with the real-time nature of transactional communication. - **Frequency capping**, because transactional messages are informational or operational and are expected to be sent whenever the triggering action occurs. - **Coupons**, **recommendations**, or **promotional** content, due to strict content restrictions that limit transactional messages to purely informational communication. - **MMS** content, as transactional SMS is limited to text-only messages for reliability and speed. These constraints ensure fast, deterministic, and reliable message delivery for transactional use cases.