Vox Mobile has the Pay as you Go for what, 6 months now, without any corresponding increase in revenues.
VoxMobile IOS App offers nothing that dozens of other IOS Apps already offer.
For example Fring offers free IOS to Android video calls already.
Tango is available for Android, IOS, WinPhones and computers too.
You all know about Skype.
It's hard to compete with free