# Improved SIP Set Up

We recently rebuilt the **Buyer** > **SIP Number** set up form to be more user-friendly.

Retreaver allows you to input regular numbers (+18885551234) or SIP endpoints (sip:username@example.com). When you enter a number starting with `sip:`, the form will automatically switch to the SIP number set up form.

### SIP Number Set Up Form

The new form now has two sections:

1. **Number**: enter for example `sip:username@example.com`
2. **SIP Username and Password**: these optional fields are used to authenticate with the SIP server.
3. **SIP Headers**: pass any additional headers you need, for example authentication or passing data to buyers PBX system

#### SIP Number vs Username and Password

For a SIP target, the value in Number like `sip:username@example.com` is the destination SIP address we dial. In other words, the `username` in the URI is the user/extension/address part of where the call should go, not the authentication login by itself.

The SIP Username and SIP Password fields are separate. When you fill them in, our system passes them as outbound SIP authentication credentials to the provider when placing the call. If you leave them blank, we still dial the SIP URI in `Number`, but we do not derive auth credentials from that URI and we do not send SIP auth unless those form fields are explicitly set.

So the practical difference is:

- `sip:username@example.com` tells us where to send the call
- `SIP Username` / `SIP Password` tell us how to authenticate with that SIP server, if authentication is required

#### SIP Headers

A common SIP Header use case is routing the call differently on the buyer's PBX based on metadata.

Example: you send a call to:

```
sip:agentqueue@example.com
```

and include a SIP Header like:

```
X-Campaign-ID: 1234

X-Publisher-ID: 5678
```


Their SIP server can read those headers and decide things like:

- send calls from campaign `1234` to a specific queue
- prioritize certain publishers
- save metadata to a dialer/CRM

Read more in our guide [How to Route Calls to a SIP Address](https://learn.retreaver.com/guides/how-to-route-calls-to-a-sip-address)