Microsoft closed the Skype for Windows Phone.
Currently, the app is still functioning, but to download it anymore.
As a replacement, you must download to smartphone Skype Preview for Windows 10 Mobile. The reason for this transition lies in the unprofitability of work of the program, which previously functioned on the basis of peer to peer networks, but to better control messenger it is necessary to abandon the customary system.
But in the case of this innovation to support Windows Phone is losing its profitability due to the small number of its users. The functioning of Skype for Windows Phone 8/8.1 will be completely eliminated by the beginning of next year.