Here's a list of the top 10 best iPhone apps that let you make free VoIP calls: JaJah. ... nimbuzz. ... MO-Call. ... Skype. ... Talkatone. ... TruPhone. ... Vopium. ... magicApp. One of the more popular SIP/VoIP apps for iPhone is the magicApp, made by the company that makes magicJack It uses a person's actual phone number to make calls. More items...