> For the complete documentation index, see [llms.txt](https://herd-security.gitbook.io/herd-security-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://herd-security.gitbook.io/herd-security-docs/simulations/voice-simulations/limits.md).

# Voice Simulation Limits

Where voice simulations work, where they don't, and how edge cases show up in your results.

Worth knowing before you plan a campaign — and before you read too much into a single result.

* **United States and Canada only.** Numbers outside the US and Canada can't be called. For teams elsewhere, [WhatsApp phishing simulations](/herd-security-docs/simulations/whatsapp-phishing-simulations.md) accept any international number.
* **English only.** The text message, the call script, and the disclosure are all delivered in English.
* **Forwarded numbers may not register a read-back reliably.** If someone's number forwards to another service (Google Voice, for example), the simulation may not reliably detect that they read the code back. Treat a pass on a forwarded number with a little caution.
* **A disconnected number counts as No answer.** It shows up in results as a pass, not as a failure to reach the person — so a cluster of **No answer** results is worth checking against your phone numbers in the [Directory](/herd-security-docs/users/users.md) before you read it as good news.

{% hint style="info" %}
Phone numbers usually reach Herd through your identity provider sync, so the fix for most of these is upstream: keep mobile numbers current in your directory. See [Before You Start with Voice Simulations](/herd-security-docs/simulations/voice-simulations/before-you-start.md#people-have-a-mobile-number-on-their-profile).
{% endhint %}