Can you explain the various call types?

• Free Calls – Calls between Zeyi users are routed totally across the internet.
• Wi-Fi/mobile data – Calls are routed over the Internet via your Wi-Fi or 3G/4G data connection to Zeyi, where we connect you to the telephone network and the person you are calling. Use this method when you have a good internet connection.
• Local Access – This method is only used when you are in your home country, using a SIM card from that country. Zeyi connects using your local GSM minutes. This is a great way to use Zeyi, especially if you are out of range of a Wi-Fi hotspot and have a monthly bundled minutes allowance.
• Callback – You click to call your contact as normal and Zeyi seamlessly ‘calls you back’ then connects you to the number you are calling. For use in countries where Local Access is not available. Callback calls are slightly more expensive as there are two parts to each call. The app requires a very small amount of data to initiate the call.