sms Operation

Send SMS and MMS messages via Twilio, Vonage, or AWS SNS with template rendering, batch processing, and E.164 validation. The sms operation handles text messaging for OTP codes, alerts, notifications, and two-factor authentication with 98% open rates and instant delivery.

Basic Usage

operations:
  - name: send-otp
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${input.phone}
      body: Your verification code is: ${input.code}

Configuration

config:
  provider: string           # twilio, vonage, aws-sns
  from: string              # Sender phone number (E.164 format)
  to: string | string[]     # Recipient(s) (E.164 format)
  body: string              # Message text (max 160 chars for 1 segment)
  mediaUrl: string[]        # MMS media URLs (Twilio only, optional)
  accountSid: string        # Twilio Account SID
  authToken: string         # Twilio Auth Token
  apiKey: string            # Vonage API Key
  apiSecret: string         # Vonage API Secret
  accessKeyId: string       # AWS Access Key ID
  secretAccessKey: string   # AWS Secret Access Key
  region: string            # AWS Region

SMS Providers

Twilio (Recommended)

Industry-leading SMS provider with 99.95% uptime and global coverage:

operations:
  - name: send
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: +1234567890
      body: Your verification code is 123456

Setup:

Sign up at twilio.com
Get Account SID and Auth Token from console
Purchase a phone number or create Messaging Service
Set secrets:

wrangler secret put TWILIO_ACCOUNT_SID
wrangler secret put TWILIO_AUTH_TOKEN
wrangler secret put TWILIO_PHONE_NUMBER

Pricing:

US/Canada: $0.0079/SMS
UK: $0.04/SMS
India: $0.0057/SMS
Full pricing

Rate Limits:

Standard: 100 SMS/second
Messaging Service: 1,000 SMS/second
Free trial: 1 SMS/second

Vonage (formerly Nexmo)

Cost-effective SMS with strong international coverage:

operations:
  - name: send
    operation: sms
    config:
      provider: vonage
      apiKey: ${env.VONAGE_API_KEY}
      apiSecret: ${env.VONAGE_API_SECRET}
      from: "Acme"                     # Alphanumeric sender ID
      to: +442071234567
      body: Your code is 123456

Setup:

Sign up at vonage.com
Get API Key and Secret
Set secrets:

wrangler secret put VONAGE_API_KEY
wrangler secret put VONAGE_API_SECRET

Pricing:

US: $0.0057/SMS
UK: $0.0331/SMS
Lower than Twilio in many regions

AWS SNS

Integrate with AWS infrastructure:

operations:
  - name: send
    operation: sms
    config:
      provider: aws-sns
      accessKeyId: ${env.AWS_ACCESS_KEY_ID}
      secretAccessKey: ${env.AWS_SECRET_ACCESS_KEY}
      region: us-east-1
      from: +1234567890
      to: +1234567891
      body: Alert: Server CPU at 95%

Setup:

Enable SNS in AWS Console
Create IAM user with SNS permissions
Set secrets:

wrangler secret put AWS_ACCESS_KEY_ID
wrangler secret put AWS_SECRET_ACCESS_KEY

Phone Number Format

All phone numbers MUST use E.164 format:

+[country code][number]

Valid Examples:

US: +1234567890
UK: +442071234567
France: +33123456789
Japan: +81312345678
India: +919876543210

Invalid Examples (will be rejected):

1234567890 - Missing + prefix
+1 (234) 567-8900 - Contains formatting
+1-234-567-8900 - Contains dashes
001-234-567-8900 - Wrong prefix

Common Use Cases

OTP Verification

operations:
  # Generate OTP
  - name: generate-otp
    operation: code
    config:
      code: |
        const code = Math.floor(100000 + Math.random() * 900000).toString();
        return { code, expiresAt: Date.now() + 300000 }; // 5 minutes

  # Send OTP
  - name: send-otp
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${input.phone}
      body: Your verification code is ${generate-otp.output.code}. Valid for 5 minutes.

  # Store for verification
  - name: store-otp
    operation: storage
    config:
      type: kv
      action: put
      key: otp:${input.phone}
      value: ${generate-otp.output.code}
      ttl: 300                         # 5 minutes

Two-Factor Authentication

ensemble: send-2fa-code

inputs:
  userId: string

operations:
  # Get user phone
  - name: get-user
    operation: storage
    config:
      type: d1
      query: SELECT phone FROM users WHERE id = ?
      params: [${input.userId}]

  # Generate 2FA code
  - name: generate-code
    operation: code
    config:
      code: |
        return { code: Math.floor(100000 + Math.random() * 900000).toString() };

  # Send 2FA SMS
  - name: send-2fa
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${get-user.output.results[0].phone}
      body: |
        Your MyApp verification code is: ${generate-code.output.code}

        This code expires in 10 minutes.
        Never share this code with anyone.

  # Log attempt
  - name: log-attempt
    operation: storage
    config:
      type: d1
      query: |
        INSERT INTO auth_attempts (user_id, code, created_at)
        VALUES (?, ?, datetime('now'))
      params:
        - ${input.userId}
        - ${generate-code.output.code}

outputs:
  success: true
  code: ${generate-code.output.code}

System Alerts

operations:
  - name: alert-admin
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${env.ADMIN_PHONE}
      body: |
        [ALERT] ${input.alert_type}
        ${input.message}
        Time: ${new Date().toISOString()}

Order Notifications

operations:
  - name: notify-customer
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${input.customer_phone}
      body: |
        Hi ${input.customer_name}! Your order #${input.order_id} is ready for pickup.
        Total: $${input.total}

        Questions? Reply to this message.

Appointment Reminders

operations:
  - name: send-reminder
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${input.patient_phone}
      body: |
        Reminder: You have an appointment tomorrow at ${input.appointment_time}.

        Reply C to confirm or R to reschedule.

Batch Sending

Send personalized SMS to multiple recipients:

operations:
  # Fetch customers
  - name: get-customers
    operation: storage
    config:
      type: d1
      query: |
        SELECT phone, name, balance
        FROM customers
        WHERE opt_in_sms = true
        LIMIT 100

  # Send batch SMS
  - name: send-batch
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      batch:
        recipients: ${get-customers.output.results}
        phoneField: phone              # Field containing phone number
        template: |
          Hi {{name}}, your account balance is ${{balance}}.
          Reply STOP to unsubscribe.
      rateLimit: 5                     # 5 SMS per second

Output:

{
  sent: 98,
  failed: 2,
  messageIds: ["SM123...", "SM124...", ...],
  errors: [
    { phone: "+1234567890", error: "Invalid phone number" },
    { phone: "+1234567891", error: "Blocked number" }
  ]
}

MMS (Multimedia Messages)

Send images and media with Twilio:

operations:
  - name: send-mms
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${input.phone}
      body: Check out this product!
      mediaUrl:
        - https://example.com/product-image.jpg
        - https://example.com/product-specs.pdf

Supported Media:

Images: JPG, PNG, GIF
Video: MP4, 3GP
Audio: MP3, WAV
Documents: PDF
Max size: 5 MB per file
Max files: 10 per message

MMS Pricing:

US/Canada: $0.02/MMS (vs$ 0.0079/SMS)
International: Varies by country

Template Rendering

Use Liquid templates for dynamic content:

operations:
  - name: send-welcome
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${input.phone}
      template: liquid
      body: |
        Welcome {{ name | capitalize }}!
        Account balance: {{ balance | money: "USD" }}
        {% if premium %}You have premium access.{% endif %}

Rate Limiting

Control sending rate to respect provider limits:

operations:
  - name: send-batch
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      batch:
        recipients: ${input.recipients}
      rateLimit: 3                     # 3 SMS per second

Recommended Rates:

Twilio Free Trial: 1 SMS/sec
Twilio Standard: 10 SMS/sec
Twilio Messaging Service: 100 SMS/sec
Vonage: 10 SMS/sec
AWS SNS: 20 SMS/sec

Error Handling

Retry on Failure

operations:
  - name: send
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${input.phone}
      body: ${input.message}
    retry:
      maxAttempts: 3
      backoff: exponential           # 1s, 2s, 4s delays

Fallback Provider

operations:
  # Try Twilio first
  - name: send-twilio
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${input.phone}
      body: ${input.message}

  # Fallback to Vonage
  - name: send-vonage
    condition: ${send-twilio.failed}
    operation: sms
    config:
      provider: vonage
      apiKey: ${env.VONAGE_API_KEY}
      apiSecret: ${env.VONAGE_API_SECRET}
      from: "Acme"
      to: ${input.phone}
      body: ${input.message}

outputs:
  sent: ${send-twilio.success || send-vonage.success}
  provider: ${send-twilio.success ? 'twilio' : 'vonage'}

Validate Phone Numbers

operations:
  # Validate E.164 format
  - name: validate
    operation: code
    config:
      code: |
        const phone = ${input.phone};
        const e164Regex = /^\+[1-9]\d{1,14}$/;

        if (!e164Regex.test(phone)) {
          throw new Error('Invalid phone number format. Use E.164: +1234567890');
        }

        return { valid: true };

  # Send if valid
  - name: send
    condition: ${validate.output.valid}
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      to: ${input.phone}
      body: ${input.message}

Handle Batch Errors

operations:
  - name: send-batch
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      from: ${env.TWILIO_PHONE_NUMBER}
      batch:
        recipients: ${input.recipients}

  # Log failed sends
  - name: log-errors
    condition: ${send-batch.output.failed > 0}
    operation: storage
    config:
      type: kv
      action: put
      key: sms-errors:${Date.now()}
      value: ${send-batch.output.errors}

outputs:
  sent: ${send-batch.output.sent}
  failed: ${send-batch.output.failed}
  successRate: ${(send-batch.output.sent / (send-batch.output.sent + send-batch.output.failed)) * 100}

Testing

Test with TestConductor

import { describe, it, expect } from 'vitest';
import { TestConductor } from '@ensemble/conductor/testing';

describe('send-otp', () => {
  it('should send OTP via SMS', async () => {
    const conductor = await TestConductor.create({
      projectPath: './conductor',
      mocks: {
        sms: {
          'send-otp': {
            success: true,
            messageId: 'SM123456',
            status: 'sent',
            provider: 'twilio'
          }
        }
      }
    });

    const result = await conductor.executeAgent('send-otp', {
      phone: '+1234567890',
      code: '123456'
    });

    expect(result).toBeSuccessful();
    expect(result.output.messageId).toBe('SM123456');
  });

  it('should handle invalid phone number', async () => {
    const conductor = await TestConductor.create({
      projectPath: './conductor'
    });

    const result = await conductor.executeAgent('send-otp', {
      phone: 'invalid',
      code: '123456'
    });

    expect(result).toBeFailed();
    expect(result.error).toContain('Invalid phone number');
  });
});

Mock SMS Provider

const conductor = await TestConductor.create({
  mocks: {
    sms: {
      '*': {                           // Mock all SMS operations
        success: true,
        messageId: 'mock-sms-id',
        status: 'sent',
        timestamp: new Date().toISOString()
      }
    }
  }
});

Best Practices

1. Keep Messages Short

# Good: 160 characters or less
body: Your code is 123456. Valid for 5 minutes.

# Bad: Too long (3 segments = 3x cost)
body: |
  Hello! Your verification code for accessing your account on
  our platform is 123456. This code will expire in 5 minutes.
  If you did not request this code, please ignore this message.

2. Include Opt-Out Instructions

# Good: Include unsubscribe
body: |
  Hi ${name}! Order #${orderId} is ready.
  Reply STOP to unsubscribe.

# Bad: No opt-out
body: Hi ${name}! Order #${orderId} is ready.

3. Validate Before Sending

# Good: Validate E.164 format
operations:
  - name: validate
    operation: code
    config:
      code: |
        if (!/^\+[1-9]\d{1,14}$/.test(${input.phone})) {
          throw new Error('Invalid phone');
        }
        return { valid: true };

  - name: send
    operation: sms

# Bad: No validation
operations:
  - name: send
    operation: sms
    config:
      to: ${input.phone}  # Could be invalid

4. Rate Limit Batch Sends

# Good: Set rate limit
operations:
  - name: send-batch
    operation: sms
    config:
      batch:
        recipients: ${input.recipients}
      rateLimit: 5

# Bad: No rate limiting
operations:
  - name: send-batch
    operation: sms
    config:
      batch:
        recipients: ${input.recipients}

5. Store Credentials Securely

# Good: Use secrets
operations:
  - name: send
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}

# Bad: Hardcoded credentials
operations:
  - name: send
    operation: sms
    config:
      provider: twilio
      accountSid: AC1234567890  # Never do this!
      authToken: secret123

6. Use Messaging Services for Scale

# Good: Use Messaging Service for high volume
operations:
  - name: send-campaign
    operation: sms
    config:
      provider: twilio
      accountSid: ${env.TWILIO_ACCOUNT_SID}
      authToken: ${env.TWILIO_AUTH_TOKEN}
      messagingServiceSid: ${env.TWILIO_MESSAGING_SERVICE_SID}

# Bad: Single phone number (limited throughput)
operations:
  - name: send-campaign
    operation: sms
    config:
      provider: twilio
      from: ${env.TWILIO_PHONE_NUMBER}

7. Monitor Delivery Status

# Good: Log and monitor
operations:
  - name: send
    operation: sms

  - name: log-status
    operation: storage
    config:
      type: d1
      query: |
        INSERT INTO sms_log (phone, status, message_id, timestamp)
        VALUES (?, ?, ?, datetime('now'))
      params:
        - ${input.phone}
        - ${send.output.status}
        - ${send.output.messageId}

# Bad: No logging or monitoring
operations:
  - name: send
    operation: sms

8. Respect Time Zones

# Good: Check time before sending
operations:
  - name: check-time
    operation: code
    config:
      code: |
        const hour = new Date().getHours();
        // Don't send between 9 PM and 8 AM
        if (hour >= 21 || hour < 8) {
          throw new Error('Outside business hours');
        }
        return { canSend: true };

  - name: send
    condition: ${check-time.output.canSend}
    operation: sms

# Bad: Send anytime
operations:
  - name: send
    operation: sms

Common Pitfalls

Pitfall: Wrong Phone Format

# Bad: Missing + or wrong format
- name: send
  operation: sms
  config:
    to: 1234567890

# Good: E.164 format
- name: send
  operation: sms
  config:
    to: +1234567890

Pitfall: Too Long Messages

# Bad: 300 characters (2 segments = 2x cost)
body: |
  Your verification code is 123456. This code will expire
  in 5 minutes. If you did not request this code, please
  ignore this message. For support, contact us at...

# Good: 60 characters (1 segment)
body: Your code is 123456. Valid for 5 minutes.

Pitfall: No Error Handling

# Bad: No retry or fallback
- name: send
  operation: sms
  config:
    provider: twilio

# Good: Retry and fallback
- name: send-twilio
  operation: sms
  config:
    provider: twilio
  retry:
    maxAttempts: 3

- name: send-vonage
  condition: ${send-twilio.failed}
  operation: sms
  config:
    provider: vonage

Pitfall: Missing Opt-Out

# Bad: No unsubscribe info (violates regulations)
body: Special offer! Buy now!

# Good: Include opt-out
body: Special offer! Buy now! Reply STOP to unsubscribe.

SMS vs Email Comparison

Feature	SMS	Email
Open Rate	98%	20%
Delivery Speed	Instant	Minutes to hours
Cost	$0.0075-$ 0.04/msg	$0.0001-$ 0.001/msg
Length	160 chars (1 segment)	Unlimited
Media	MMS only (5 MB)	Full HTML, attachments
Best For	Alerts, OTP, urgent	Newsletters, receipts, long-form
Compliance	TCPA, GDPR	CAN-SPAM, GDPR

Troubleshooting

SMS Not Delivering

Verify phone format - Must be E.164 (+1234567890)
Check provider credentials - Ensure Account SID/Auth Token correct
Review rate limits - You may be hitting throttles
Check provider console - View delivery reports
Test with own number - Confirm basic functionality

Rate Limit Errors

# Reduce sending rate
config:
  rateLimit: 1                        # 1 SMS per second

Invalid Phone Number Errors

// Validate E.164 format
function validateE164(phone: string): boolean {
  return /^\+[1-9]\d{1,14}$/.test(phone);
}

// Remove formatting
function formatToE164(phone: string, countryCode: string = '+1'): string {
  const digits = phone.replace(/\D/g, '');
  return `${countryCode}${digits}`;
}

Message Too Long

Single SMS: 160 chars (GSM-7) or 70 chars (Unicode)
Concatenated SMS: Up to 1600 chars (10 segments)
Cost: Each segment charged separately
Solution: Shorten message or use link shorteners

Next Steps

email Operation

Compare with email

storage Operation

Store OTP codes

code Operation

Generate verification codes

Testing

Test SMS workflows

Conductor

Getting Started

Core Concepts

Building

Operations Reference

Pre-built Agents Reference

Playbooks

Reference

​sms Operation

​Basic Usage

​Configuration

​SMS Providers

​Twilio (Recommended)

​Vonage (formerly Nexmo)

​AWS SNS

​Phone Number Format

​Common Use Cases

​OTP Verification

​Two-Factor Authentication

​System Alerts

​Order Notifications

​Appointment Reminders

​Batch Sending

​MMS (Multimedia Messages)

​Template Rendering

​Rate Limiting

​Error Handling

​Retry on Failure

​Fallback Provider

​Validate Phone Numbers

​Handle Batch Errors

​Testing

​Test with TestConductor

​Mock SMS Provider

​Best Practices

​Common Pitfalls

​Pitfall: Wrong Phone Format

​Pitfall: Too Long Messages

​Pitfall: No Error Handling

​Pitfall: Missing Opt-Out

​SMS vs Email Comparison

​Troubleshooting

​SMS Not Delivering

​Rate Limit Errors

​Invalid Phone Number Errors

​Message Too Long

​Next Steps

email Operation

storage Operation

code Operation

Testing

sms Operation

Basic Usage

Configuration

SMS Providers

Twilio (Recommended)

Vonage (formerly Nexmo)

AWS SNS

Phone Number Format

Common Use Cases

OTP Verification

Two-Factor Authentication

System Alerts

Order Notifications

Appointment Reminders

Batch Sending

MMS (Multimedia Messages)

Template Rendering

Rate Limiting

Error Handling

Retry on Failure

Fallback Provider

Validate Phone Numbers

Handle Batch Errors

Testing

Test with TestConductor

Mock SMS Provider

Best Practices

Common Pitfalls

Pitfall: Wrong Phone Format

Pitfall: Too Long Messages

Pitfall: No Error Handling

Pitfall: Missing Opt-Out

SMS vs Email Comparison

Troubleshooting

SMS Not Delivering

Rate Limit Errors

Invalid Phone Number Errors

Message Too Long

Next Steps