SMS Messaging

The One Voice provides two-way SMS messaging on your Voice phone numbers. Send and receive text messages from the same numbers your team uses for calls.

Prerequisites

10DLC Registration is required before sending outbound SMS to US phone numbers. US carriers block SMS from unregistered business numbers. See 10DLC Registration below.

Canadian numbers use a different registration process (short codes or long codes with CASL compliance).

SMS Inbox

Go to Messages in the left navigation. The interface shows a conversation-style view:

• Left panel — contact list sorted by most recent message
• Right panel — full conversation thread with timestamps and delivery status

Sending a Message

1. Click New Message (+ icon)
2. Type the recipient's phone number or search contacts
3. Select which From Number to use (if your org has multiple numbers)
4. Type your message
5. Click Send

Message Status

Each sent message shows a delivery status badge:

Status	Meaning
Sent	Delivered to Telnyx; in transit to carrier
Delivered	Carrier confirmed delivery to handset
Failed	Delivery failed (see error code in message detail)
Undeliverable	Number is landline, invalid, or blocked

Receiving Messages

Inbound SMS appears in the conversation thread automatically. If you have browser notifications enabled, a notification appears for new messages even when you're not viewing the Messages page.

SMS Templates

Templates save frequently used messages and ensure consistent messaging across your team.

To create a template:

1. Go to SMS → Templates
2. Click Add Template
3. Give it a name and write the message body
4. Use {{first_name}}, {{company}}, {{ticket_id}} as merge variables (populated at send time if the contact is linked)
5. Click Save

To use a template while composing:

1. In the message compose area, click the Templates icon
2. Select the template
3. The message body is populated; edit before sending if needed

Bulk SMS

Bulk SMS lets you send a message to multiple contacts at once.

1. Go to Messages → Bulk Send
2. Choose recipients:
   • Manual entry — paste numbers or upload a CSV (phone, first_name, last_name, company)
   • Contact group — select from a saved contact group
3. Write your message or pick a template
4. Review the recipient count and opt-out exclusions
5. Click Send Now or Schedule for a future date/time

Opt-out compliance: Any recipient who previously replied STOP is automatically excluded from bulk sends. The system tracks opt-outs per your org and per phone number.

10DLC Registration

10-Digit Long Code (10DLC) is the US carrier requirement for business SMS on local phone numbers. Without registration, your messages will be filtered or blocked.

Step 1 — Register a Brand

1. Go to SMS → 10DLC
2. Click Register Brand
3. Fill in your company legal name, EIN (US tax ID), address, website, and contact email
4. Submit — Telnyx submits to The Campaign Registry (TCR); approval typically takes 1–3 business days

Step 2 — Create a Campaign

1. After brand approval, click Create Campaign
2. Choose a Use Case (e.g., Customer Care, Marketing, 2FA) — the use case determines carrier fees
3. Describe how you collect consent, what types of messages you send, and how recipients opt out
4. Submit — campaign approval takes 1–5 business days

Step 3 — Assign Numbers

1. After campaign approval, go to the campaign detail
2. Click Assign Numbers
3. Select which of your Voice phone numbers to link to the campaign
4. Save

Numbers not linked to an approved campaign will have SMS blocked by US carriers.

Campaign Status

Status	Meaning
Pending	Submitted, awaiting TCR review
Active	Approved — SMS enabled on linked numbers
Suspended	Carrier suspended the campaign (review required)
Rejected	Registration rejected — see rejection reason and resubmit

Opt-Out Compliance

The One Voice automatically handles opt-out keywords as required by TCPA and CASL:

• STOP / UNSUBSCRIBE — adds number to the opt-out list; auto-replies "You have been unsubscribed"
• START / SUBSCRIBE — removes from opt-out list if previously opted out
• HELP — auto-replies with your org name and opt-out instructions

You cannot override these automatic responses. Attempting to send to an opted-out number will return an error.

Troubleshooting SMS

Issue	Cause	Fix
Messages showing "Failed"	10DLC not registered	Complete 10DLC registration and link the number
Cannot send to certain numbers	Number is on NDNC or VoIP-only	Check if the number is a landline or VoIP (no SMS capability)
Bulk send shows 0 recipients	All recipients opted out	Review opt-out list under SMS → Opt-Out Manager
No inbound SMS received	Number not SMS-capable	Go to Phone Numbers and verify SMS capability is enabled