The company asks you to open the routes for the test. It can occur in the evening or before the weekend. According to the test result you have got an agreement for the contract signing. At the nighttime or while weekend (if you haven’t limited a client by a credit) he succeeds to send a bulk of traffic to an open route and then disappears without paying. You can prevent the loss by limiting the client with the test lines (1-2), by the credit (10 USD is enough for testing) and to look after that he was denied to access the system after the test. Even if the access remains open the credit limit won’t allow him to send more than 10 USD traffic.