---
title: "SMS Senders"
description: "The phone numbers and identities your SMS messages originate from."
url: https://www.unitpost.com/guides/sms-senders
section: Guides
updated: 2026-07-31
---
# SMS Senders

## SMS Senders

> The phone numbers and identities your SMS messages originate from.

SMS needs an origination identity the way email needs a verified domain. Start with the sandbox sender: it works immediately but only delivers to verified test numbers (a carrier rule for unverified senders). A dedicated toll-free number unlocks production sending to any US number after a one-time verification.

A sender moves through registration and verification states before it's active, and its status is re-checked at send time — a suspended or released number can't silently keep sending. Number rental is billed to your card as a recurring line item, never drawn from your usage wallet.

> **Keep marketing and OTP apart:** Carriers degrade deliverability for numbers that mix bulk marketing with time-sensitive transactional traffic. When you start sending campaigns, add a dedicated marketing sender so a blast can never slow your verification codes.

## Related

- [SMS Dashboard](https://www.unitpost.com/guides/sms-dashboard): Your SMS sending at a glance — volume and delivery over the last 30 days.
- [SMS Activity](https://www.unitpost.com/guides/sms-activity): The workspace activity stream, scoped to the SMS channel.
- [SMS Templates](https://www.unitpost.com/guides/sms-templates): Reusable SMS message templates. Coming soon.