Public advocacy groups aren't all that impressed with AT&T's justifications for limiting FaceTime access over 3G and 4G to those who spring for its costlier Mobile Share plans. Free Press, Public Knowledge and the Open Technology Institute have served formal notice to AT&T that they plan to file a net neutrality complaint with the FCC within 10 days. It's not hard to understand why, given the groups' existing pro-neutrality stances: the Free Press' policy lead Matt Wood argues that the carrier is unfairly pushing iOS users into plans they don't need, a particularly sore point for iPad-only customers that have no AT&T phones to share. We've reached out to AT&T for comment, although we're not expecting a change from its position that allowing app use over WiFi makes its restrictions okay. As for the FCC? It's mum on the current situation. A literal reading of its net neutrality rules, however, doesn't include a WiFi exemption and might not favor AT&T when Skype video is allowed and Verizon has no problems with unrestricted access.