Service Task — Send SMS 📱

Sends an SMS text message via a configured SMS provider.

Node type: serviceTask (subtype: Send SMS) Category: Integration Actor: serviceTask (2 threads)

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Description

The SMS Service Task sends text messages via Twilio, Vonage, or Amazon SNS. Phone numbers and message body support {varName} variable substitution for dynamic personalization.

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Properties

Property	Type	Required	Description
smsConnectionId	string	Yes	ID of the SMS integration
toNumber	text	Yes	Recipient phone number in E.164 format (e.g., +15551234567). Supports {varName}
message	textarea	Yes	SMS message body (max 1600 chars). Supports {varName}

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Inputs

toNumber: {customerPhone}
message: Hi {customerName}, your order #{orderId} has shipped! Track at: {trackingUrl}

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Outputs

Variable	Type	Description
{smsSent}	boolean	true if the SMS was dispatched successfully
{smsSid}	string	Provider message SID for tracking (Twilio)

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Example

{
  "nodeId": "send-sms-1",
  "name": "Send Appointment Reminder",
  "nodeType": "serviceTask",
  "properties": {
    "smsConnectionId": "int_twilio_prod",
    "toNumber": "{patientPhone}",
    "message": "Reminder: Your appointment with Dr. {doctorName} is tomorrow at {appointmentTime}. Reply CANCEL to cancel."
  },
  "timeout": {
    "duration": 15,
    "durationUom": "SECONDS",
    "action": "FAIL"
  }
}

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Connections

Condition	Connection
SMS dispatched	successFlow or sequenceFlow
Send failed	errorFlow
Timeout	timeoutFlow

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Phone Number Format

All phone numbers must be in E.164 format: + followed by country code and number, no spaces or dashes.

Format	Valid?
+15551234567	✅ Valid
+44 20 7946 0958	❌ Invalid (spaces)
5551234567	❌ Invalid (no country code)
(555) 123-4567	❌ Invalid (formatted)

If your workflow receives phone numbers in other formats, use a Script Task to normalize them before the SMS node.

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Supported SMS Providers

Provider	Notes
Twilio	Industry standard, global coverage, detailed delivery receipts
Vonage	Global reach, competitive pricing
Amazon SNS	AWS-native, cost-effective for AWS deployments

Configure the from-number and credentials in the SMS Integration.

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Character Limits

Encoding	Max per segment	Notes
GSM-7 (standard ASCII)	160 chars	Most Latin text
UCS-2 (Unicode/emoji)	70 chars	Non-Latin scripts, emoji
Multi-segment	Up to 1600 chars	Billed as multiple SMS messages

Variable substitution happens before sending — ensure the final message does not exceed 1600 characters.

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Best Practices

• Validate phone numbers before sending — use If/Else to check {customerPhone} is non-null
• Keep messages under 160 characters to avoid multi-segment billing
• Always connect an errorFlow to handle invalid numbers or provider errors
• Include opt-out instructions for marketing messages per carrier regulations
• For appointment reminders and notifications, set up a scheduled trigger rather than triggering on every event