My outgoing message says that I will never answer a call from a number I don't recognize, so, when this number calls, I just ignore it. Have no idea who they are because they never leave a message...I guess I'll be avoiding them forever!
Probably a telemarketing call. You can't block it and even if you can they ALWAYS sell your number to other companies. Who cares if it's for your work or not. DO NOT ANSWER YOUR STUPID PHONE! THAT'S WHAT A FREAKING MOBILE PHONE IS FOR......IGNORING CALLS YOU DON'T KNOW.