Do repaired iPhone's have a warranty

Hey, so first my iPhone 4 one day decided to lose cellular connectivity and would sit at 'searching' 24/7/ Multiple sim cards from different carriers were tested, to no success and the usual wipe and restore. $280NZD later, my iPhone arrived apparently being repaired.

However, two weeks later, or today, my 'repaired' iPhone has lost signal once again.

So as the title says, does a repaired iPhone have a warranty?

The original purchase warranty has since expired, hence the $280 repair cost.

Also I noted that my serial number from my old iPhone and the repaired one are both the same. Is that meant to be right?

I will be ringing Apple first thing in the morning as well. But thought I would ask. I have lost a bit of confidence in Apple's support when I was dealing with my first repair.

Thanks.

That's what I was thinking. I'll post an update after ringing Apple tomorrow. Thanks

Just an update for anyone who's interested. Apple are replacing the phone free of charge. This time, instead of me sending the phone away first, they're sending a replacement first and then I'm to send my phone away. Very happy.