Skype showing me as online - after stopping app and even after device shutdown? Scenario A:


start Skype
do some other work
shut down the Android device


Problem:
My contacts are still seeing me as being "online".
Strangely enough there seems to be no heartbeat feature implemented in Skype.
So even after 1 day my contacts are trying to call me - even though the device is powered off.

Initially I thought this symptom would occur in case i forgot to manually quit the Skype app before shutting down the device.
So i was searching for an answer how to configure Skype to automatically log off / quit when the Android device is shutting down?

But now it turned out the situation is even worse:

Scenario B:


start Skype
do some other work
quit the Skype app
shut down the Android device


After step 3 I'm still listed as being "online".
When a contact sends me a chat message it pops up.
So it means: even though Skype no longer appears in the task manager it seems to be running as a secret, invisible background task!?

And after step 4 the behaviour is the same as in Scenario A. I'm not transitioning to "offline" state.

Summary:
There seem to be 3 problems:


no heartbeat feature implemented in Skype
quitting the Skype app is not properly terminating / signing off
shutting down the Android device also is not influencing the online status


The only thing that works for me so far:
You must switch to Skype, tap on your profile, at the very bottom manually do "sign out".
That's just not bearable.

This is:
Android 4.1.2
Skype 4.9.0.45564
Skype 5.0.0.49715
Skype 5.1.0.56619
Skype 5.1.0.58677
Skype 5.4.0.5871 (at least I'm now showing as being "Away" - instead of "Online")  

2015-08-15 - the problem is back and it's even worse:
Android 5.1.1
Skype 5.9.0.14047
Even though I'm manually signing out, terminating the app and shutting down the Android device I'm still being shown as being "online"!!

--
All of the above tested @ Samsung Galaxy Tab 2 7.0 (WiFi only) / GT-P3110
OMG, I have found the following posting: http://community.skype.com/t5/Security-Privacy-Trust-and/Skype-invading-and-changing-people-s-online-status/m-p/2961695/highlight/true#M28546

According to above the "always on" concept was a deliberate decision by Microsoft:

(...) we have changed the way online status presence works:
(...) we are showing you as online to your contact even when you left or
force killed the app on your mobile phone (...)


They admit that certain scenarios need fixing:

Now we've identified a few scenarios where this is simply misleading:
 - you've switched off your device
 - you've disconnected from the internet (e.g. by switching to airplane mode
   and you are somewhere mid flight)

In these occasions you are right now still shown online and we are working to
make Skype presence indicator be meaningful in these scenarios as well.


This is just so weird.
They should certainly make it configurable.

For now the only way to disconnect is to manually "sign out".
Quitting the app isn't sufficient. Shutting down the device is neither.

Status Update (2015-08-15):
The problem is back. And it's even worse!
Even though i manually sign out, quite the Skype app and shut down the Android device I'm still being shown as "online"!
Observed with: Skype 5.9.0.14047 @ Android 5.1.1