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

> ## Agent Instructions
> Use Stable documentation by default. Honor an explicit Beta request or a URL under /docs/beta/. If the requested version conflicts with the installed CLI package or API origin, clarify the target before writing integration code.
> Pages under /docs/beta/ document Beta; other product pages document Stable. Keep the CLI package, commands, API origin, and credentials within the selected version. State the documentation version in your answer.
> For MCP search, always pass version: Stable or version: Beta. Unfiltered search mixes both versions. For filesystem reads, keep Beta queries under /beta/ and exclude /beta/ from Stable queries; discover paths before reading them.
> The public docs base is https://photon.codes/docs. Convert MCP page paths to public URLs under that base, preserving /beta/ when present. Read https://photon.codes/docs/skill.md for version selection and https://photon.codes/docs/llms.txt for the version indexes.

# SMS best practices

> Understand short-code limits, verification-code filtering by line type, and safe use of Photon numbers with third-party services.

Before using a Photon number to receive a login or verification code, check its
line type and the sender's number. SMS numbers, iMessage lines, and personal
WhatsApp lines do not handle verification codes the same way.

## Short codes are not supported

Photon numbers cannot send messages to short codes or receive messages from them.
Short codes are the short numeric addresses some services use for automated text
messages.

A verification code sent from a short code will not arrive, even on an SMS
number where general verification-code filtering is off. Do not build a workflow
that depends on sending to or receiving from a short code.

## Verification-code filtering depends on the line type

A one-time passcode (OTP) is a temporary code used for sign-in, account
verification, or account recovery.

| Photon line type | OTP handling |
| - | - |
| SMS number | Photon does not apply general OTP filtering. The WhatsApp Business registration-code exception below still applies. |
| iMessage line | Photon filters OTP codes. Do not rely on these lines to receive login or verification codes. |
| WhatsApp line | Photon filters OTP codes. Do not rely on these lines to receive login or verification codes. This channel is [not yet released](https://docs.photon.codes/docs/beta/messaging/whatsapp.md). |

The SMS filtering policy does not guarantee that a third-party service will
accept the number or deliver a code.

> [!NOTE]
>
> WhatsApp Business registration codes sent to Photon SMS numbers are reserved
> for connections through Photon. They do not appear in SMS history or inbound
> message events. Complete verification through the
> [Photon WhatsApp Business setup flow](https://docs.photon.codes/docs/beta/messaging/whatsapp-business.md), not
> through another WhatsApp provider.

## Avoid using SMS numbers for third-party account registration

We do not recommend using Photon SMS numbers to register accounts with
third-party services. Use a number or another authentication method that the
service supports instead.

You are responsible for complying with each third-party service's terms of
service. Do not use Photon numbers to bypass its registration, verification, or
account restrictions. Receiving a code does not grant permission to use the
number with that service.

If a login code does not arrive, first check the line type and whether the sender
uses a short code. Then follow the third-party service's supported verification
or account-recovery process rather than repeatedly requesting codes on an
unsupported line.


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.