Called my cell...no message.

this number keeps calling me and when i call it back it just does nothing and then goes to busy signal

I have been receiving calls from this number - no messages and number is disconnected.

I got a call from this number also. No message, but when I called back someone answered and said "hello my name is Robert, thank you for calling me back how are you doing today?" I figured it was a sales call so hung up.