The Call Flow Designer can write to your 3CX in two ways. Knowing the difference is what keeps your live numbers safe. The badge next to the page title tells you which ways are open: “Sandbox: your numbers are not changed”, or “Sandbox and live: you choose when you publish”.
| Test in sandbox | Publish live | |
|---|---|---|
| Menus, queues, ring groups, smart steps | created with sandbox numbers (8900 to 8949 by default) | created with real numbers (8000 to 8899 by default) |
| Your phone number (inbound rule) | never changed | pointed at the new menu, as the last step |
| Callers notice | nothing | the new flow |
| How to try it | dial the sandbox number from a desk phone | call the number |
| Shown on the card | Sandbox 8900 | DN 8000 |
| Undo | Clear sandbox objects | Undo last publish |
| Who can | any administrator | needs live publishing switched on for the account |
Both go through the same review. Nothing is written until you confirm, and a live publish asks twice.
If step 5 disappoints: History… › Undo last publish. Two minutes, no Admin Console.
A flow remembers two sets of numbers, sandbox and live. Testing a change never touches the live objects, and publishing live never touches the sandbox objects. The header shows both stamps: “Published 8.9.2026, 13.22 by Name” and “Sandbox test 8.9.2026, 13.40 by Name”.
Sandbox objects stay on 3CX until someone removes them. They cost nothing, but they show up in the Admin Console. Clear sandbox objects on the flow list asks “Remove every object the designer created in sandbox mode?”, deletes them for all flows, and the flows forget their sandbox numbers. Live objects are never touched by it.
Next: Publishing a call flow.
