Does the iPhone 5 has the same antennae problems as the 4?

I have been using my iPhone 5 for a few months now and I have noticed that sometimes the connection drops and even worse, it drops without me being informed of it!

It stays in a LifeProof case that's waterproof, dustproof, shockproof and snowproof, so I'm wondering if it can have anything to do with the case.

I doubt it, I'm just mentioning it for the sake of mentioning all circumstances.

When I try to call or send a text, I'm unable to do so, but resetting the iPhone through Airplane modus works. It's just that I cannot see that I can't receive messages or calls!

I do not use Voice-mail.

I haven't got any problem with Wi-Fi btw, that works fine and keeps me informed if people can't reach me.

This is my first smartphone, so I don't know it it has anything to do with my phone in itself or my operator.

I live in The Netherlands and my operator is Telfort which uses the network of KPN.

The problem seems to be more frequent during the afternoon, but lately I have been having it in evenings too.

It happens when I travel, like today, but also when I stay at home like last friday.

Does it have anything to do with my iPhone?

Does it have anything to do with my LifeProof case?

Does it have anything to do with my telcom provider?

Any hints would be welcome (no, I'm not going to take of the case, the iPhone is way too much fragile.)!