I have Zoiper on my mobile phone since years, using it for calls via VPN if I am travelling. Otherwise I do not use it at all, and I never receive calls. For a long time it was with Android 4, since 6 months on a new phone it is Android 7. Never had any serious trouble, and never changed a thing. I did not call since many months.
Now suddenly the day before yesterday the battery of my phone was completely empty - the phone just lying around! I reloaded during the night - and a couple of hours later it was the same. The phone is not old, and normally a battery is good for at least 2-3 days.
In the "Power" settings I found no obvious guilty party, but in the WLAN I saw that since the last two days, Zoiper has generated more than 16 GB traffic! The graphic display showed a curve gradually raising, until two days ago it was "shooting upwards".
So it seems clear: Since the moment that my phone is draining the battery like mad, Zoiper is also generating excessively much WLAN traffic!
And of course my question is: WHY??
I changed the settings now to not stay on in the background, and I manually stopped the application. I will have to see if the internet traffic is now again back normal!? At least I see already a little change in the curve, but will have to wait a few days now.
I want to repeat that I did NOTHING with Zoiper since months, neither use it nor change any settings.
Thanks for any useful hint!
If it turns out that is a buggy automatic update, or whatever kind of virus that managed to "attach" to Zoiper (if this is at all possible) I may have to delete the app altogether and try to find an alternative - if possible.