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Send an SMS message as part of your workflow. Messages appear in Unibox alongside other conversations.

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Configuration

FieldRequiredDefaultDescription
Phone numberYes—Which workspace phone number to send from. Select from your purchased numbers.
Recipient typeYesContactContact sends to the trigger contact’s phone. Custom lets you enter a specific number.
Custom phoneIf custom—Phone number in E.164 format (e.g., +14155551234). Only shown when recipient type is “Custom”.
MessageYes—The message text. Supports {{variables}}. Max 1,600 characters.

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Variables

Use variables to personalize the message: 
Hi {{firstName}}, thanks for chatting with us today.
We'll send over the details to {{email}} shortly.
Available variables: {{firstName}}, {{lastName}}, {{email}}, {{phone}}, {{businessName}}, plus any trigger data or previous step outputs.

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Compliance

The first SMS sent to a new phone number automatically includes an opt-out footer with your workspace info and instructions to reply STOP. This is required for compliance and happens automatically — you don’t need to add it to your message. Two independent toggles control this, under Phone Numbers → Compliance: the company/sender name and the opt-out notice. Both are on by default. You can disable either one per workspace (for example, if your carrier already appends opt-out language), but leaving them on is strongly recommended — opt-out text is generally an A2P/carrier requirement and turning it off makes compliance your responsibility.

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Opt-out enforcement

If the contact replied STOP (or any of STOPALL, UNSUBSCRIBE, CANCEL, END, QUIT) to the workspace number you’re sending from, the action fails with an opt-out error and the SMS is not sent. The check is per (contact, phone number) — a contact opted out from one number can still be reached from another. A contact who later replies START, UNSTOP, or YES is opted back in automatically and the workflow can send again. Carrier-level opt-outs (received via Telnyx webhooks) are enforced the same way. See Unibox → SMS opt-out handling for full opt-out behavior.

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Limits

LimitValue
Max message length1,600 characters
Daily SMS per workspace100
Segment length160 chars (GSM-7) or 70 chars (Unicode/emoji)
Messages longer than one segment are sent as multi-part SMS and count as multiple segments.

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Checks

Before sending, the action verifies:
  • The contact has a phone number
  • The contact is not on the Do Not Call (DNC) list
  • The contact has not opted out from the selected workspace number
  • The phone number is active in your workspace
  • The daily SMS limit hasn’t been reached
If any check fails, the action fails with a descriptive error.

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Example

Follow-up after a call:
  1. Trigger: Conversation ended → Agent Type: voice
  2. Condition: Outcome equals “completed”
  3. Action: Send SMS
    • Phone number: Your workspace number
    • Recipient: Contact
    • Message: “Hi {{firstName}}, great speaking with you! As discussed, here’s the link to get started: https://example.com/signup”