Two calls from that number on 2:00am and 2:10am - on one on the other end. It hands up when I answer the call

Got a call from this number on my husband's cell phone two nights in a row at 2:40AM.
I googled it and got only Russian looking web pages!

Try calling it back and the operator says it can not be completed as dial even if you add the 1 before it.....it will not go through!

Called 6 times in 12 hours no one on the other side!