An FTC commissioner warned cellphone content providers they need to do a better job of disclosing the costs consumers incur when clicking or downloading services for their mobile devices.

Speaking yesterday at the start of a two-day Federal Trade Commission forum on mobile devices, the commissioner, Jonathan Liebowitz, said the FTC intends to step in to take enforcement action against deceptive or unfair content offers.

eMarketer forecasts that mobile social networking will grow from 82 million users in 2007 to over 800 million worldwide by 2012.