Just as a warning I give every time I can, CHEATERS FIND A WAY.
I could see calls and texts too through the phone company, so my ex took his affair underground using the chat feature on a scrabble game him and OW downloaded and played together. None of that shows up on the phone bill, and I certainly wasn't suspicious of a freaking scrabble game..
Just sayin, if your WH *knows* how you are tracking him, then he may find another way.. And they could be communicating quite often with a lot going down that you don't know about. For example, maybe they are communicating another way and she's pissed he isn't leaving you for him, and so she's just trying to piss him off and get him into trouble knowing you can see the messages and calls..
I'm guessing this is why if you're trying to R, it's best not to reveal all your sources.. Seems to me that most waywards and their affair partners try to continue communicating after D-Day without the betrayed knowing..
And FWIW, I agree with Gonna. I don't go calling back unknown numbers. They can either leave me a message or not. Seems fishy to me.. I hope he's being honest with you..
And please don't have a revenge affair. If you want someone else, just tell your WH that and divorce him. Don't go sleeping with someone else just to piss him off. It's not healthy for you, and you can't just assume it won't hurt the person you have the affair with.. Stay true to yourself. If you aren't the type of person that would cheat, don't start being one now..