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SMS in Custral is two-way: outbound messages route through a Twilio number you’ve connected to a Channel, and inbound messages land in the same Conversation thread alongside email, voice, and chat. You can text from the dedicated Messages inbox, the floating Messages widget, the reply box inside any SMS conversation, or the mobile app.

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How SMS is wired

  • A connected Twilio number becomes a Channel of type sms.
  • Outbound and inbound messages thread into one conversation per contact number, so replies land in the thread the customer started.
  • Inbound messages arrive on a Twilio webhook and are matched to an existing conversation or start a new one; routing rules decide which user(s) get assigned.
  • All send paths (Messages screen, widget, reply box, mobile, automations) go through a single core, so threading and delivery stay consistent.

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A2P 10DLC registration (required for US delivery)

US carriers filter or block texts from unregistered businesses. Register your workspace in Settings → Phone & SMS → Compliance:
  • Submit your business (Brand) and messaging (Campaign) details. Brand types: Standard (needs an EIN), Low-Volume Standard, or Sole Proprietor (no EIN, lower throughput).
  • Carrier vetting takes hours to days; the Compliance tab shows live Brand and Campaign status. Until the Campaign is active, the new-message composer shows a “register to send” notice.

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Opt-out (STOP / START)

Opt-out handling is automatic and mandatory: a recipient who replies STOP (or UNSUBSCRIBE) is opted out, and Custral refuses further texts to them (recipient_opted_out). START / YES opts them back in.

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Limits

  • Twilio enforces per-segment rate limits and per-day caps. Custral surfaces Twilio’s limits directly.
  • MMS (image/video attachments) is supported on US/CA numbers only; inbound media is stored and rendered inline in the thread.

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Troubleshooting

When reporting an issue, include the request id shown in the error toast. It links the in-app error to the server logs.