---
title: Test mode
description: Build against test keys that never touch live money or live networks.
group: concepts
order: 1
---

A test key (`scn_test_...`) talks to a test wallet and a simulated network. Responses, statuses, fees, timing and webhooks match live, so nothing in your code changes when you go live except the key.

## Choosing an outcome

In test mode the last four digits of the phone number decide what happens:

| Ends in | Outcome |
| --- | --- |
| `0000` | Permanent failure: `failed`, with a failure code |
| `1111` | Temporary failure: tried elsewhere, and with nowhere else to go, `failed` |
| `2222` | Unknown outcome: `pending` while we check its status |
| `3333` | `pending` first, then `successful` |
| `4444` | `pending` first, then `failed` |
| anything else | `successful` |

## What stays separate

Test and live never mix. A test key cannot see live transactions, spend the live wallet or reach a live line, and the dashboard shows each mode on its own.