> ## 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.

# Inbound calls

> Register an inbound route and receive calls from a Spectrum iMessage line.

Inbound calling sends calls received by your Spectrum iMessage line to your
SIP application.

You must register inbound routing in the dashboard. Configuring outbound SIP
credentials does not create the inbound route automatically.

## Before you start

You need:

* A Spectrum project.
* An iMessage line in that project.
* A SIP client, PBX, or voice application that can receive calls over TCP.
* The inbound routing details requested by the dashboard.

WhatsApp numbers cannot be used for Spectrum Voice.

## Set up inbound calling

<Steps>
  <Step title="Open the project">
    Sign in to the [Spectrum dashboard](https://app.photon.codes) and select the
    project that owns the iMessage line.
  </Step>

  <Step title="Open inbound voice registration">
    Open the project's inbound voice registration and choose the iMessage line
    that should receive calls.

    Make sure you select an iMessage line. WhatsApp numbers are not supported.
  </Step>

  <Step title="Register the inbound route">
    Enter the SIP routing information requested by the dashboard and save the
    registration. The dashboard registration tells Spectrum where to send an
    incoming call.
  </Step>

  <Step title="Configure your SIP application">
    Configure the receiving application with the inbound values shown in the
    dashboard. Set the SIP transport to TCP.

    Do not use UDP, TLS, or a `sips:` URI. They are not currently supported.
  </Step>

  <Step title="Keep the SIP application available">
    Start the SIP application and keep its connection active so it can accept
    an incoming call.
  </Step>

  <Step title="Place an inbound test call">
    From another phone, call the iMessage line registered in the dashboard.
    Confirm that your SIP application receives the call and that audio works in
    both directions.
  </Step>
</Steps>

## What each registration does

The word "registration" can refer to two different settings:

| Registration     |              Required? | Purpose                                                     |
| ---------------- | ---------------------: | ----------------------------------------------------------- |
| Inbound route    | Yes, for inbound calls | Routes calls from an iMessage line to your SIP application. |
| Business profile |                     No | Helps identify outbound traffic and reduce flagging risk.   |

Registering a business profile does not create an inbound route. Registering
an inbound route does not register the business profile.

## Before going live

* The inbound route is saved under the correct project.
* The selected number is an iMessage line, not a WhatsApp number.
* The SIP application uses the routing values shown in the dashboard.
* The transport is TCP, not UDP or TLS.
* The SIP application stays connected and ready to receive calls.
* A test call reaches the application and has working two-way audio.

## Troubleshooting

### No inbound call arrives

Check that the inbound route is saved for the exact iMessage line being called.
Then confirm that the SIP application is running and connected over TCP.

### The wrong project or line receives the call

Open the inbound registration in the dashboard and verify both the selected
project and iMessage line. The inbound route is tied to that selection.

### The SIP application tries UDP or TLS

Select TCP explicitly in the SIP application. Automatic transport selection
can choose a protocol that Spectrum Voice does not support.

### I configured outbound calls, but inbound does not work

Outbound credentials and inbound routing are separate. Return to the dashboard
and register the inbound route for the iMessage line.