There are surprisingly few Skype alternatives. vBuzzer almost does it, but they charge monthly fees for non-usage, as well as joining fees and even exit fees.

There are not many globally available VoIP services, available on both iOS and Android, that can call regular phone lines with rates comparable to or less than Skype. Until that happens, the old dinosaur telcos (with their walled-garden phone call and SMS services) will get a few more years of life.