It is a device capturing and controling all the signals, which are being created by the whole system, especially the made and received phone call signals. The device is mostly used for connecting regular phone system with the Internet and backwards.
In order to take care of the billing process and keep track of calls it is essential to have some sort of computer software. The system you are planning to select should allow the manager setting up prices per minutes and show the reports of calls that were made by the customers. For the operator the installed software has to provide a possibility to control the booth status, what amount to charge and generate invoices or receipts.