I see you posting on the spyware thread. I feel for you. My FWW arried out 95% of her A on her iphone 5. The other 5% was in POSOMs bed.
I could never get into the phone, she guarded it with her life. And deleted everything the second she read it. She made a critical error once and drunk facebook messaged OM, but by accident she messaged my father, who [weeks later] clued me into the possibility of an A.
Odds are that she isn't texting or calling OM, it's messaging within FB or WWF or iChat, or endless other messaging apps. So, phone records won't help. You should still try. Over the coarse of three months my W texted OM ONE TIME. Talk about a needle in a haystack. Be prepared for a lot of homework if you get the records (reverse lookups). With a company owned phone, you can't jailbreak it to put on the spyware. Well, you could, but you better get the goods fast because there could be legal he77 to pay if/when company IT finds out.
Hindsight being 20/20, there were a few other things i COULD have done if I suspected something (which I didn't). I could have hired a PI. He would have easily picked up on the 5% that wasn't on her phone. I could have put a keylogger on our PC to get her FB and email password. She used it only rarely but I could have tricked her into logging in. POSOM gave her a necklace that she wore all the time and told me a friend gave it to her. I could have called the friend to "thank" her for the necklace "my wife loves it so much, where did you you get it? I'd like to get her some matching earings". Granted this just gives circumstantial evidence, but it's evidence. Leave no stone unturned. There are clues...find them.
Does she ever leave it unattended and locked? Could you guess her passcode? My DS8 knew FWW passcode so he could play games. She didn't give him the code, he just watched her. Sneaky little cuss. If she has a pattern lock you can generally see finger oils on the screen protector. As long as she locks it immediately after unlocking it you may have a chance. If she never leaves is unattended you are SOL, and need a PI. Or, wait for her to make a error. My guess is she will...be ready.