> This page is part of the [Customer.io documentation](https://docs.customer.io). For the complete index, see [llms.txt](https://docs.customer.io/llms.txt).
> Last updated: July 30, 2026

# SMS: Frequently Asked Questions

## Does Customer.io manage my provider account?

No. Whether you send through Twilio, Sinch, Infobip, or Vonage, we can’t set up or manage your provider account for you.

Your provider account includes your sender numbers and other things that we can’t manage on your behalf—so you can make changes to your senders, keywords, and so on without having to wait on us to make changes to your account. The exception is if [we set you up](/messaging/channels/sms/get-started/#customerio-as-your-provider): then we provision your numbers and work through registration with you, and you don’t manage a provider account at all.

## What countries can I send SMS messages to?

Country coverage depends on your provider, but the providers we support cover most countries worldwide. Depending on where you send messages, there are a couple of things you should know:

1.  [MMS messages](/messaging/channels/sms/send-messages/#mms) only work for the US and Canada—and through Vonage, the US only.
2.  Providers publish their own guidance for international sending—for example, Twilio’s guide to [sending messages outside of North America](https://www.twilio.com/docs/messaging/guides/sending-international-sms-guide) and its [country-specific restrictions](https://help.twilio.com/articles/223133767-International-support-for-Alphanumeric-Sender-ID). If you already know where you plan to send messages, check your provider’s coverage before you start sending.

## Can an SMS trigger a conversion in my automations?

**[Conversions in Customer.io](/messaging/send/automations/conversions/)** track the last email or communication sent before the user performs an event, enters a conversion segment, or leaves a conversion segment. If you track users performing an action, entering a segment, or leaving a segment after receiving an SMS, then the SMS is considered *converted*.

## What happens when someone opts out of SMS?

When someone texts an opt-out keyword like STOP, CANCEL, or UNSUBSCRIBE to one of your senders, we mark them as opted out and stop sending them SMS—from every provider you’ve connected. See [Opt-outs](/messaging/channels/sms/keyword-opt-out/) for the full keyword list and behavior.

Your provider and the carriers may also filter opted-out recipients on their side. For example, [Twilio handles STOP, STOPALL, UNSUBSCRIBE, CANCEL, END, and QUIT](https://support.twilio.com/hc/en-us/articles/223134027-Twilio-support-for-STOP-BLOCK-and-CANCEL-SMS-STOP-filtering-) in accordance with industry standards, and blocks messages to those recipients from your Twilio phone number regardless of what we send.

## What if a person stopped receiving messages but wants to receive them again?

Texting START or UNSTOP to your sender opts them back in, both in Customer.io and with your provider. See [Opt-outs](/messaging/channels/sms/keyword-opt-out/) for details.

## How can I see if my SMS was delivered successfully?

You would want to view successfully completed messages in the Automation **Sent tab**, which will show a state of Sent, Failed, Bounced, or Delivered. You can also filter for these SMS messages in the **Delivery Log**.

[More about SMS metrics in Customer.io](/messaging/channels/sms/metrics/)

## Can I segment based on SMS?

Yes! To segment for an SMS, you can use the segment builder as normal. One SMS condition covers your messages from every provider:

[![image.png](https://docs.customer.io/images/image%28339%29.png)](#064926e3aa57fa45f833dcbe0795c01f-lightbox)

## Do you support short codes?

Yes we do! Short codes sync from your provider just like any other sender. For example, if you’ve leased a short code through Twilio, or Twilio has done so on your behalf, it syncs like any other Twilio number.

To learn more about how short codes work with Twilio (as well as look at pricing information), you can learn more [on Twilio’s documentation page](https://support.twilio.com/hc/en-us/articles/223182068-What-is-a-short-code-).

## Can I send using Alphanumeric IDs?

Yes, through Twilio! But there are a few important things to keep in mind when you do:

1.  **Enable the feature in Twilio first!** You can add these in Customer.io, but if you haven’t [enabled it in your Twilio project settings](https://support.twilio.com/hc/en-us/articles/223181348-Getting-started-with-Alphanumeric-Sender-ID), the message will fail.
2.  **They’re one-way**: Your customers cannot reply to them.
3.  **Opt-in/opt-out**: Customers receiving these should have opted in to your service and be informed on how to opt out.
4.  **They’re not supported in all countries, including the USA**: If you try to send to an [unsupported country](https://support.twilio.com/hc/en-us/articles/223133767-International-support-for-Alphanumeric-Sender-ID) from an Alphanumeric Sender ID, your SMS will fail to send. Note that some require sender ID pre-registration with Twilio.

If you’ve enabled Twilio in Customer.io and want to send using Alphanumeric IDs, [here’s how](/messaging/channels/sms/sender-phone-numbers/#alphanumeric-id). For other providers, your senders come from what we sync from your provider account—configure sender IDs with your provider, then [sync again](/messaging/channels/sms/get-started/#manage-your-connections-and-delivery-settings).

## Can I use Liquid to determine the Sender ID?

Yes, with Twilio—Liquid code can be added as a [Manual Sender ID](/messaging/channels/sms/sender-phone-numbers/#using-a-manual-sender-id) to accomplish this. For example, if you wanted to send from a different phone number depending on which Customer Success Manager is assigned to the customer, you could insert a code block such as:

```fallback
{% if customer.CSM == "stephen" %}
+1647STAPHEN
{% else if customer.CSM == "zack" %}
+1800GOTZACK
{% else %}
+1800CUSTOMR
{% endif %}
```

Manual sender IDs—including Liquid senders—are a Twilio-only feature; other providers only send from the senders we sync.

## Can I send WhatsApp messages through Twilio in Customer.io?

Yes, but only if you integrated with Twilio before July 30, 2026. Keep in mind, when sending WhatsApp messages through Twilio, the message should align with one of Twilio’s [predefined categories](/messaging/send/workflows/webhooks/action/). After you create a WhatsApp message template in Twilio, you will need to submit the template for approval as described [here](https://www.twilio.com/docs/whatsapp/tutorial/send-whatsapp-notification-messages-templates#creating-message-templates-and-submitting-them-for-approval). Once approved, you can send WhatsApp messages in Customer.io by following the instructions [here](/messaging/channels/whatsapp/get-started/).

If you integrated with Twilio on or after July 30, 2026, you have to [integrate with your Meta/Facebook Business account](/messaging/channels/whatsapp/get-started/#set-up-meta) to send WhatsApp messages through Customer.io.

## Do shortened links expire?

Shortened links expire after 90 days. We reuse paths, but only within your workspace so that someone interacting with an old link will never see links or information sent from another workspace.

But reusing links means that if you send a shortened link, you should avoid using URLs that include personal details (like a customer’s name). If you send links to personal information, you should require that people log in to your site to access the information.

*   *   [Does Customer.io manage my provider account?](#does-customerio-manage-my-provider-account)
    *   [What countries can I send SMS messages to?](#what-countries-can-i-send-sms-messages-to)
    *   [Can an SMS trigger a conversion in my automations?](#can-an-sms-trigger-a-conversion-in-my-automations)
    *   [What happens when someone opts out of SMS?](#what-happens-when-someone-opts-out-of-sms)
    *   [What if a person stopped receiving messages but wants to receive them again?](#what-if-a-person-stopped-receiving-messages-but-wants-to-receive-them-again)
    *   [How can I see if my SMS was delivered successfully?](#how-can-i-see-if-my-sms-was-delivered-successfully)
    *   [Can I segment based on SMS?](#can-i-segment-based-on-sms)
    *   [Do you support short codes?](#do-you-support-short-codes)
    *   [Can I send using Alphanumeric IDs?](#can-i-send-using-alphanumeric-ids)
    *   [Can I use Liquid to determine the Sender ID?](#can-i-use-liquid-to-determine-the-sender-id)
    *   [Can I send WhatsApp messages through Twilio in Customer.io?](#can-i-send-whatsapp-messages-through-twilio-in-customerio)
    *   [Do shortened links expire?](#do-shortened-links-expire)

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