Samsung galaxy note 2 - phone freezes during a call

I hope you can help me, i have Samsung galaxy note 2 and when i make or receive a call the line comes and goes and then i can't ear anymore (at this point i thought it was my network) but then the 'call screen' freezes; it doesn't respond - it does only when the other side hungs up. This has been happening in the last few weeks but the strange thing is my husband has the same problem and he has Samsung a3.
I thought about the phone software but i have kitkat and my husband has lollipop, mine is rooted but my husband's is not, mine is few years old but my husband's is few months old. I don't get it!!!
Could it be a particular app we have installed?
Please help !!! :(