OPC (Online Phonebill Calculator) Cost: $15 Get the full version     Trial version     Developer's Website Contacting third-party download site please wait. If your download does not start, click here, or get the full version Descriptions OPC (Online Phonebill Calculator): If you connect to the internet using a modem (or any form of dial-up connection) then OPC is the ideal tool to monitor your phonebill costs due to internet calls. It does everything from generating charts/reports/logs to automatically timing connections.