[ iOS ] Main Changes in Version 1.4.0 are the following.

• A ringback tone starts ringing sooner when you make a call.
• You can start talking sooner when you answer a call.
• SkyPhone is now available on iPad.
• Improved stability and bug fixes.

The connection speed (in making and receiving calls) gets improved.

A ringback tone starts ringing sooner and connection gets faster. If the other person uses an older version, the connection speed is as usual.
Besides, you can start talking sooner than before after you tap "Answer."
Furthermore, the vibration lasts longer while the app is not launched, so you can detect incoming calls more easily than before.
Note: That applies to iOS 8 or later.