Your claim that just because Skype is connected it will drain very fast your battery is pretty bogus, the way software works in modern OSes like Linux is that the app runs and then blocks (normally waiting for I/O, timers, etc.) until rescheduled, if the app doesn't block itself then the Linux scheduler will put it to sleep to avoid starvation. Skype as the majority of network apps will sleep waiting for events or expiration of it's timers. Powertop reports 10ms timers for Skype on x86 which are not that good but it's a hell lot of time to sleep for a CPU, I'm pretty confident Skype is not a battery drainer per se. Network traffic via WiFi or Bluetooth drains more the battery but Skype traffic when not in-call is negligible. Obviously there are a lot of factors so YMMV.