Unless you have some wish to know what is being said to each other once you verify the affair, there is really no reason to actually read every SMS. If you can get the detailed cell phone bill, it generally has a list of numbers that messages have been sent to and received from and that alone is enough to bust the infidels.
You see, you don't have to prove that an affair is going on by explaining away every possible objection the WS makes when you confront them. They already KNOW they are having an affair. Once you have enough information to show a pattern of contact that is out of the range of "normal" between the WS and OP, it is not necessary to uncover a lot of details about what they discuss. Suffice it to say, they are flirting, making suggestive comments and planning their next time together. It's what a WS and OP DO...
Once a BS goes to the WS for confrontation, the very first attempt to get away with it is almost always..."It isn't like that. We're just friends..."
Gaslighting, pure and simple.
When I confronted my wife, I had a list of phone calls by time and date, traces of emails, pictures, poems and a bunch of other stuff. I really had none of the materials themselves, but was able to ID one picture based on file name that she forgot to change (she was covert enough to change almost all the rest of them to cover her tracks) So I spent a day laying out this elaborate timeline that showed she called OM, then sent him a picture via email, called again later, sent him a poem she wrote at a certain time etc. By dropping the picture I could identify in her lap as part of my confrontation, I didn't have to know everything, just enough to convince her that I knew.
And her first attempt at gaslighting me was "We're just friends When I asked about the more than just suggestive pictures, she said "We're just getting to know each other"
DOH!
Friends getting to know each other for the first time share pictures of kids, pets, gardens...not body parts that the public isn't supposed to see.
You see, when you bust them, they KNOW they have been busted. You don;t have to have the kind of evidence you would need to take it to court. You only need the trail, not the details of what happened.
If I come home late and my wife asks. "Where were you?" and I answer "I worked late" and she saw my car parked at the casino, she doesn't have to know if I was playing Black Jack or baccarat. She knows I was gambling. The same applies to an affair. Once a pattern of contact has been established, you can assume it is an affair, especially if the WS tries to cover his/her tracks and explain it away.
And only the trail left by SMS contact is required to show continued contact, since NONE is the requirement and ANY contact is too much contact.
As far as looking at a phone, everybody has to go to sleep some time. You just have to wait for an opportunity, maybe stay up late one night, set the WS up a time or two, etc. But if you can get the call records, you really don't need all of that.
Mark