If you have household or renter's insurance, the company MAY offer a rider that would cover loss/theft/damage/device failure for an iphone. State Farm does NOT cover cell phones but others do.
Otherwise, AC+ or Squaretrade for damage or device failure - no loss or theft coverage. If you use a standard credit card to purchase the phone (e.g., AMEX, Discover, Visa, MC), check to see what their coverage is as well for purchases made since they may cover loss or theft, at least within the first few months of purchase.
Stay far, far away from the cell carriers' TEC/Asurion. They are an unmitigated scam.