Its probably cause AT&T is currently testing femtocell so in short yes iCall would be a competing product/app so thats probably why its still on hold..
http://www.dslreports.com/shownews/ATT-Looking-For-Femtocell-Testers-100100
In reply to: "More iPhone apps you can't have: Newber and iCall"
January 8, 2009