Your iPhone 5, like the few previous models, uses an elegant metal case in order to be lighter and slimmer.
However, since it is a cellphone (there is a clue is in the name), it requires a full-duplex radio to work.
Since Mr Ive is not a RF engineer and is far, far more important in Apple than the RF engineers, their no-doubt-continuous whining about the impact the case would have on reception was ignored.
Hence Antenna-gate and the ongoing crapness of iPhone reception. even Jon Stewart, a no tech knowledge whatsoever American TV show host wondered aloud "Why don't phones work as phones?". he has an iPhone obviously as a rather large proportion of our cousins across the pond do apparently - no judgement.
OTOH, Nokia, that company that failed because the phones were not pretty enough until too late, made RF systems that worked (and still work) beautifully.
Their cases are almost all made of monoblock polycarbonate, RF transparent and tough as hell. But, not as pretty (perhaps, I like them and it does allow more colours etc.).
When Nokia decided to introduce the (very nice looking indeed) 925, I was distinctly worried by the all-metal-case aspect of he design. Silly me, Nokia's RF engineers incorporated the metal shell into the antenna design and improved the reception if anything.
This is all a result of R&D spending, while often wasted (I saw some of it), it produces staggering things like a 41MP camera unit with OIS in a stupidly small 10MM package and makes a Xenon flash work in a slimmer phone but defies physics (or something).
And yes, without even checking, I know the 1020 will make phone calls well. I also know that when I tell people I am in a train station or noisy pub, they will say "I can't hear anything else" because the noise cancelling hardware (and software perhaps) is also brilliant.
Then I can take a picture of the pub (or train station) without a flash using that OIS to prove I am where I say I am, phew!