@Rob Miracle -
According to this page: http://docs.coronalabs.com/legacy/api/library/ads/show.html
It says:
iAds
iAds supports the following ad types on all iOS devices:
iAds supports the following ad banner type only on iPad:
Has this changed in current Corona SDK releases? Sorry haven’t tested it personally, I’m still doing final tweaks and changes. Hope to implement an ad network in a couple days.
According to that , adMob is the only network that supports Interstitial on both iphone and ipad. But I’d prefer using iAD if it’s available on both.