My developer and I had previously tried to get interstitial adverts loading on iPhone and iPad, however only managed to get this working on iPad.
During our testing we discovered that interstitials weren't supported on iPhone, but since the release of iOS7 some people now say this is possible.
However I can't find any decent documentation on this. This Stack question has got me wondering again though iAd & Admob Interstitial Integration on iPhone
So, are full screen interstitials possible on iPhone using iAds?