Free Wi-Fi Calling Without Sim and Internet

Abstract Private businesses began to rely more and more on telephone communication as the contemporary telephone networks took shape. A lot of people choose to launch their own business. so that they could manage calls coming from within the company. Voice telephony on mobile devices is provided at a fee using a service provider like GSM, or at a lesser cost using an IP service provider. The purpose of this project is to build and implement a telephony programme that employs WLAN (Wireless Local Area Network) or Peer-to-Peer (P2P) WIFI as a free method of communication between mobile phones. Phone numbers will be converted into IP addresses by the 3CX Phone System software using a correlation between the most recent address books made available on mobile devices.The system will permit voice communications from users. The current setup does not support conference calls or call waiting, only one call per connection. We describe various security services that are appropriate to VoIP and make the case that end-to-end authentication and encryption ought to be offered by default.