Number tried to call me very quickly, faster than I could respond. Quick google search does not make me want to try and call them back, especially with the "One Ring" call scams I've heard of where an unknown number tries to run up charges on your phone bill when you answer / call back.
For anyone else curious: 777 is an INVALID AREA CODE, not associated with any geographic location (at least, not in the US it's not!) -- i.e. someone using the 777 area code is spoofing / obfuscating their phone number on purpose. I can't imagine anything good coming from someone using that kind of phone number.