# Starting session and authentication

To establish a FIX session, you must first connect to Revolut FIX Gateway and submit the [**`A` (Logon)**](/docs/guides/exchange-fix-api/introduction-to-the-exchange-fix-api/system-overview#session-level-messages) message.

| FIX session parameter                        | Description                                                  |
| -------------------------------------------- | ------------------------------------------------------------ |
| `Host`                                       | DEV: revx-fix.revolut.codes<br/>PROD: revx-fix.revolut.com   |
| `Port`                                       | 9999                                                         |
| `SSL Required`                               | Yes                                                          |
| <code><b>49</b> SenderCompID</code>          | Provided to you                                              |
| <code><b>56</b> TargetCompID</code>          | always equals `REVX` constant                                |
| <code><b>108</b> Heartbeat Interval</code>   | `30` (recommended)                                           |
| <code><b>553</b> Username</code>             | Provided to you                                              |
| <code><b>554</b> Password</code>             | Provided to you                                              |