WiFi phones that use the 802.11b or 802.11g standards transmit at 2.4 GHz. Phones that use the 802.11a standard transmit at 5 GHz. When you make a call on a WiFi phone, you dial the number of the person you want to call, just like you would with a cell phone.If you're calling another VoIP user, you may enter a VoIP address instead of a phone number, depending on the service provider's requirements.rom their user interface to how they work, WiFi phones are a lot like cell phones. Like a basic cell phone, a WiFi phone has a printed circuit board (PCB) that connects: 1  A processor. 2  A speaker and a microphone.