Cheapest international calls? Skype?
 

Is skype the cheapest/best? Especially for pay as you go rates?
How do you call to international numbers?

Viber works fine to me and it definitely cheaper than Skype

I use Voxofon on my Android phone to call intl numbers. You dial a local number which routes you to your intl destination. Good price and great quality.

Skype is like 0,7 cent/minute, how much is that service? Sounds like at least the price of local call?

Hmm, lets say calling to UK's landline is 1 cent/minute, that is fine. But calling to mobiles it is around 15 cents/minute.
Times more expensive than skype, no?

I use voip.ms
Not sure the exact rates but it is quite cheap. You need to setup your own softphone, I use different ones on my iPhone and laptop.

I use G3Telecom .10 minutes for free without asking your credit card info.

Skype

However just started using Ultra mobile as my primary phone carrier (T-Mobile MVNO)

Unlimited Calling, Text, Data and free international calling to select countries and 1000 minutes - $29 bucks/mo

or

$19 minus the 1000 minutes