AT&T Inc. on Wednesday introduced a new slate of wireless plans that raised prices for its most frugal customers, while lowering costs for its biggest data users.

The company’s new mobile share advantage plan also will eliminate overage fees, opting instead to slow wireless speeds for customers who have topped their monthly data allowances. That move follows the model used by discounters T-Mobile US Inc. and Sprint Corp., which have dropped overage charges. Verizon Communications Inc. charges its subscribers a fee to...