This number keeps calling my cell phone. I never answer as it is not a number I recognize. A man has left messages a few times, claiming it is urgent I call back, that it is an important business matter, yet he never explains further than that.

If it's important and they leave messages, why not answer?  Telemarketers don't leave messages...

LOL!  I guess we all know why they are calling you two!

Its Mainstreet equitys collection office. Some type of litigation office.