The setup order

Set up the side calls leave from first, then the side they come from. That way, when the first customer call arrives, everything it needs already exists.

Step	Page	Why now
1	Connect a GSM gateway	Ports are where calls go. Nothing can be routed without them.
2	Add a SIP carrier	Optional. Only if you also send calls to carriers.
3	Routing groups	Put the ports and carriers a customer may use into one list.
4	Rates	Give every destination you sell a price and a cost.
5	Billing accounts	Prepaid or postpaid, with a credit limit.
6	Customers	Last: once the customer exists, its calls are accepted.
7	Your first test call	Prove each step worked before real traffic.

The panel’s own Guide page (Ctrl K → guide) shows the same steps and ticks them as you go.