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SMS Applet Guide

The SMS applet sends an SMS message to the caller or a specified number during a call flow. Use it for post-call confirmations, missed call notifications, appointment reminders, or any scenario where you need to send a text message as part of a voice call workflow.

tip

For sending SMS programmatically outside of call flows, use the SMS API. The SMS applet is specifically for sending messages as part of an active call flow.

How the SMS Applet Works​

When a call reaches the SMS applet in your flow:

  1. The applet composes an SMS message using the configured template
  2. The message is sent to the specified recipient (caller's number by default)
  3. The call flow immediately continues to the next applet (SMS sending is asynchronous)
  4. The SMS is delivered independently of the call -- even if the call ends, the SMS still arrives
Call Flow ──► SMS Applet (sends SMS) ──► Next Applet (continues immediately)
                    │
                    └──► SMS delivered to recipient's phone (asynchronous)
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The SMS applet does not pause the call flow. The message is queued for delivery and the flow proceeds to the next step without waiting for SMS delivery confirmation.

Configuration​

Basic Setup​

  1. Drag the SMS applet onto the Flow Builder canvas
  2. Click the applet to open the Properties Panel
  3. Configure the recipient, sender, and message content
  4. Click Apply

Configuration Fields​

SettingRequiredDescription
To NumberYesRecipient's phone number (default: caller's number)
Sender IDYesDLT-registered sender ID for the SMS
Message BodyYesThe text content of the SMS
DLT Template IDYesThe DLT-registered template ID for the message
DLT Entity IDYesYour DLT-registered entity ID

Recipient Options​

OptionDescription
Caller's numberSends the SMS to the person who called (default)
Called numberSends to the ExoPhone number (rarely used)
Custom numberSends to a specific phone number you configure
DynamicUses a number from a Passthru applet response (advanced)

Message Body​

The message body supports static text and dynamic variables:

VariableReplaced WithExample
{CallFrom}Caller's phone number+919876543210
{CallTo}Called number (ExoPhone)+914412345678
{CallSid}Unique call identifierabc123def456
{DateTime}Current date and time2024-01-15 10:30

Example message:

Thank you for calling Acme Corp. Your reference number is {CallSid}.
For further assistance, call us at 1800-XXX-XXXX.
DLT Compliance Required

All SMS sent through the SMS applet must comply with TRAI's DLT regulations. This means:

  1. Your entity must be registered on the DLT platform
  2. The message template must be pre-approved
  3. The sender ID must be registered
  4. The actual message content must match the registered template

Messages that fail DLT validation will not be delivered. See the DLT Guide for registration instructions.

Use Cases​

1. Post-Call Confirmation​

Send a summary SMS after a successful call:

Greeting ──► Connect (agent) ──► SMS ("Thanks for contacting us. Ref: {CallSid}") ──► Hangup

2. Missed Call Alert​

Send an SMS when the caller could not reach an agent:

Greeting ──► Connect (agent) ──► (no answer) SMS ("We missed your call. We'll call back soon.") ──► Hangup

3. Appointment Reminder​

After booking an appointment via IVR, confirm with an SMS:

IVR ──► Passthru (book appointment) ──► SMS ("Your appointment is confirmed for...") ──► Hangup

4. Lead Capture from Missed Call​

For missed call lead generation campaigns:

Greeting (brief ring) ──► SMS ("Thanks for your interest! Visit acme.com/offer") ──► Hangup

5. Post-Survey Thank You​

After a caller completes an IVR survey:

IVR (survey questions) ──► Passthru (save responses) ──► SMS ("Thank you for your feedback!") ──► Hangup

DLT Template Setup​

Before using the SMS applet, register your templates with the DLT platform:

Step 1: Register Your Entity​

If not already done, register your business entity on the DLT platform. See DLT Registration.

Step 2: Create a Template​

Register a message template with variables:

Template: "Thank you for calling {#var#}. Your reference number is {#var#}. For support, call {#var#}."
Template ID: 1107166XXXXXX
Category: Transactional

Step 3: Get Template Approved​

Submit the template for approval. Approval typically takes 1 -- 3 business days.

Step 4: Configure in SMS Applet​

Enter the Template ID and Entity ID in the SMS applet configuration.

SMS Delivery and Billing​

AspectDetails
Delivery timingSMS is queued immediately; delivery depends on carrier (typically 1 -- 30 seconds)
BillingSMS is billed at your standard per-SMS rate
DND handlingTransactional SMS is delivered to DND numbers; promotional SMS is blocked
Character limit160 characters (GSM-7) or 70 characters (Unicode) per segment
Long messagesMessages exceeding the limit are split and billed as multiple segments
Delivery statusAvailable via SMS API or SMS Reports

Error Handling​

ErrorCauseImpact on Call Flow
DLT validation failureTemplate or entity not registeredSMS not sent; call flow continues
Invalid recipient numberNumber format incorrectSMS not sent; call flow continues
Insufficient balanceAccount credits depletedSMS not sent; call flow continues
Carrier rejectionCarrier-level filtering or DND blockSMS not sent; call flow continues
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SMS applet errors do not affect the call flow. If an SMS fails to send, the call flow continues to the next applet as normal. Check SMS Reports to track delivery status of SMS sent from call flows.

Best Practices​

  1. Keep messages short -- Stay within 160 characters to avoid multi-segment billing
  2. Use transactional SMS -- For call-flow-triggered messages, transactional SMS ensures delivery to DND numbers
  3. Register templates in advance -- DLT template approval takes time; register templates before building the flow
  4. Test with a real number -- Make a test call and verify the SMS arrives
  5. Include a reference number -- Use {CallSid} so the recipient can reference the call
  6. Do not spam -- Only send relevant, expected messages as part of the call interaction