How do you determine which phone is having issues?

When you are on a phone call whether it is cell or land line and there is a probably with hearing the other person or just some connection issue, how can you determine which phone is having the problem?

My husband is always saying to me, you gotta replace your phone, it isn't working right. But is it? Could it be his phone? Quite honestly I know my work blackberry sometimes has problems depending where I am using it. But he says the same thing about my landline work phone.

So is there a way to determine if it is really my phone? I just figure if I am on a landline and he is on a cell and moving, it would more likely be a cell phone connection issue. Basically I don't want to report an issue with my work if there really is not a problem with it.