Skype problem

Hi,

I have Skype problem. When I call in Skype from my mobile phone Samsung Ace 3 S7275R android, to another same phone
the other phone does not answer and my phone does not even ring and the connection is not be done. The same happens when
I call from my PC to the same android phone and when the screen is deactivated on the phone the
Phone almost every time does not answer. Sometime the same happens from this phone
To the PC. I'm using the latest Skype version. What should I do to fix it?

Email:mariosgeorgiou@cablenet.com.cy