Push notifications aren't reliable enough to be available during the brief period when a person is calling. A push notification that is set to go out at 9am mig

Push notifications aren't reliable enough to be available during the brief period when a person is calling. A push notification that is set to go out at 9am might go out at 9am, but it also might go out at 9:01, 9:02, etc. My guess is that this is why Skype doesn't use them.