FaceTime (or heck, even Fring), but Tango's multi-platform videocalling app is still a very real alternative. So real, in fact, that it was just used in an episode of The Big Bang Theory as a highly fictional (and severely busted) character makes an outlandish videocall to a mythical group of friends. Or was it all just a dream? Hop on down to the source link (and fast-forward to the 13th minute) to find out.
Tango videocalling app stars on The Big Bang Theory