How to get rid of strange constant calls to the phone and viber from similar city numbers?

Question

Viber

Recently, a friend in Germany receives calls to Viber and actually regular phone calls from numbers like 003804490050 ** (the last two digits are always different). It looks like a Kyiv landline phone number. But then how do calls come to Viber? In addition, after a little googling, I determined that in Kiev there are no phones starting with 900.
Calls occur several times per hour. Usually a couple of seconds and immediately knocked down. They call day and night. A friend tried to call them back (I know that you shouldn’t do this at all, but I already tried), they shoot down.
What could it be and how to deal with it?

Answer 1

let aFirewall on the phone put and create a white list. Or let the mask cut off the left numbers

Answer 2

Contact those. support. Most likely there are errors somewhere.
I'm serious. Write to your mobile operator.

Answer 3

blacklist on phone

Answer 4

kotlerman
Good afternoon! I've had the same problem for a week now, they've been calling and it's not clear why. Viber technical support does not respond to applications.
Did you somehow solve the problem 3 years ago?
The option to put some kind of blocker is not entirely suitable, because. I use viber on my computer too.
Blacklisting doesn't help either. Each time the call comes from a new number.