Direct Dial calling allows the caller to enter the international  call prefix, country calling code and telephone number and then be directly connected to the person they are calling. This is how you dial when using your regular mobile service. Direct Dial Calling is standard on the OneSimCard Europe & More, OneSimCard Universal and eSIM.

Callback calling also allows the caller to enter the international  call prefix, country calling code and telephone number. After the called number is entered, the user immediately receives an incoming call connecting the user to person called. Callback is very simple to use and allows for low cost calling on the OneSimCard Plus and OneSimCard Expedition (formerly Data & Roam). Callback does not increase the connection time. It is the same as with Direct Dial.

In countries where the cost of using mobile Internet Data is below 20 c/MB, the cost of using SIM VoIP over the data is comparable or less than the actual calling rate from the country.

As a rule of thumb, the SIM VoIP will use 1MB /Min of talk time. So, if the cost of Data in the country is 10 c/MB, then 1 minute SIM VoIP call will cost you 12 cents /minute. You need to have a 3G connection in order for SIM VoIP to work this way.