To initiate the process, you will need the phone’s IMEI number, this may be obtained by pressing #6# on the cell phone. With the IMEI, go to www.nokialockcode.com/calculate.php enter IMEI and hit calculate; there is your master code. This is one of many ways to get to the messages.
It is very logical to access these messages under these conditions if you suspect your significant other; it is the right thing to do; it is called testing your relationship. What if your partner was cheating, and such evidence exists, and all you had to do was hack to get to it? So in certain circumstances it may be OK. Though you are aiming to figure out whether or not your spouse or partner is being crafty, which is very understandable, there are people out there that seek gratification from peeking into others lives. Whether your request is justifiable is merely circumstantial, and only you know the answer to that.