The whitepages.com has reverse phone search, which is pretty accurate.
If he's done it once, there's a good chance he'll do it again. That "feeling" you have is your intuition telling you something.
I went through this not too long ago. After catching him once, a year later, I started getting that funny feeling again. He accused me of being paranoid, so I did not check the numbers. I noticed excessive calls to one particular number and when I confronted him, he said that it was a friend of his. (and the "other" numbers were people borrowing his phone at work) UNTIL... One of my kids asked me why he jumped at his cell phone when it rang and would not let them touch it.. I called the number and a woman answered. I hired a detective and found that it was a coworker (had worked with her 6 months) and continued communication after that. We are in the process of separating. I can not live with someone I don't trust. I can do a lot better.
