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.
COMTALK delivers DID/DDI numbers & termination in Denmark (but also most of the world) We offer SIP and are also MVNO, which means low cost calls to the Danish Celluar networks