Have blocked this number now .... after receiving several calls whereby phone rings for few seconds .... try ringing back and message bank is full ..... most annoying.
A scam of some sort

Another call today one ring??

Rings, doesn't leave message.

likewise phone rings once a day, only 1 ring, answer, no one there.
I have tried calling them back on viber, after 7 rings it goes dead.
I know there was a similar situation I call backed on my mobile and it was someone trying to sell something.

Had a couple of calls from this number, as soon as I answer it hangs up. Called back and call went straight to mailbox.

Phone rings once,no message,have had about 5 or 6 calls the same from this number.