This number has dialed my cell phone 6 times so far today.  No one at the other end, no voice messages left.

They change the end numbers was 0789 now 0786 scam more then likely...no voice mail ever left.

This number called me early am, no one on the other end, no msg. For what purpose ?

Check your telecom provider, they may have a block call list available to you. If you have Charter do this:

Dial *60
Press 1 to enable the charter call block list
Then press 2 to add a number to the list
Type in phone number without international code "1", just XXX-XXX-XXXX then press the # sign
Press 6 to exit the call

After about a dozen numbers the list is full and you can't add anymore. Scroll through the call log on your phone and write down numbers from the most recent to the past. Dial into the call block service again, press 4 to clear the list, then press 2 and add each number starting from the most recent backward. This keeps your block list up to date.

Enjoy