How to organize calls abroad (in Belarus), a greater number of calls to Russia landlines and mobiles.
1) employees have androids which will stand the app (calls via Internet).
2) should be "centralization" (e.g., a username and password to connect to the server or shared account).
3) I want the ability to restrict calls to certain country codes, etc.
4) the service should work through the corporate wifi or via the Internet. anywhere (this is in case the option with the purchase of servers or other equipment).
P. S> Maybe there's something similar to Skype, Viber, ...