> ## Documentation Index
> Fetch the complete documentation index at: https://help.cloudtalk.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Limitations receiving OTP and 2FA SMS messages

> Find out why CloudTalk numbers may not be able to receive your one-time passwords

> [!NOTE]
>
> CloudTalk is built for scalable, secure business communication, but due to how third-party OTP systems work, **we cannot guarantee that OTP or Two-Factor Authentication (2FA) codes sent from *other* companies will be delivered to CloudTalk phone numbers**.
>
> This article explains why and what you can do instead.

***

## Why is this a limitation?

CloudTalk provides **VoIP (Voice over Internet Protocol)** phone numbers — these are virtual numbers, not tied to a SIM card or mobile carrier.

Most platforms that send OTPs (like banks, social media, and software tools) have **strict delivery policies** and often block or deprioritize delivery to VoIP numbers.

Here’s why:

* **OTP senders often whitelist only mobile carrier numbers.** VoIP numbers are typically excluded.

* **SMS aggregators and routing systems may block virtual numbers** due to anti-fraud policies.

* **Some services silently filter or drop messages** when the number doesn’t meet their criteria.

This means OTP and 2FA codes sent **from other companies** may not reach your CloudTalk number — even if SMS is working normally otherwise.

## What *is* supported?

You can absolutely **send outbound automated messages** using your CloudTalk numbers as part of your own business workflows.

However, receiving verification codes from third-party services (Amazon, banks, etc.) **is not guaranteed**.

| **Use Case** | **Supported?** |
| - | - |
| Sending outbound OTPs via CloudTalk SMS | ✅ Yes |
| Receiving marketing or customer messages | ✅ Yes |
| Receiving OTPs/2FA from third-party apps | ⚠️ Not guaranteed |
| Using CloudTalk number for secure logins | ⚠️ Not recommended |

## Best alternatives

For services that require verification codes, we recommend:

* Using a **mobile number from a mobile carrier** instead of a VoIP number.

* Setting up an **authenticator app** (e.g. Google Authenticator, Authy, or Microsoft Authenticator).

***

*Need help or have a question?* Just reach out through our [Support portal](https://support.cloudtalk.io/hc/en-us/requests/new?ticket_form_id=26305535257884) — we’re here for you.


## Related topics

- [Cannot Send or Receive SMS](https://help.cloudtalk.io/en/articles/12959333-cannot-send-or-receive-sms.md)
- [Using CloudTalk numbers externally in WhatsApp and WhatsApp Business mobile apps](https://help.cloudtalk.io/en/articles/8957786-using-cloudtalk-numbers-externally-in-whatsapp-and-whatsapp-business-mobile-apps.md)
- [WhatsApp Not Sending or Receiving Messages](https://help.cloudtalk.io/en/articles/13333950-whatsapp-not-sending-or-receiving-messages.md)


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