Any US resident is asking for trouble if you promote a sports book. Not only is sports betting over the phone covered by 1961 wire act, but US Court of Appeals has ruled that sports betting over the internet is covered by wire act. That same ruling said that casino gaming, poker, etc is not covered by the law, since congress couldn’t have anticipated “blackjack being played over the phone”
Steve Badger’s site has the ruling posted here:
http://www.playwinningpoker.com/online/poker/legal/appeals.html