"We apologize for any inconvenience but the BlackBerry 4G PlayBook Tablet that was announced in January for summer availability will no longer be coming to the Sprint network," Sprint said in a statement.

The operator currently offers a Wi-Fi-only version of the tablet. A customer could connect that device to a Wi-Fi hotspot that uses WiMax on the back end, such as the Mifi, and connect to Sprint's WiMax network that way.

Sprint said it was a mutual decision between the operator and Sprint not to offer the WiMax PlayBook.

RIM said it will focus on LTE, the 4G technology more widely adopted, instead of WiMax. "RIM has decided to prioritize and focus its 4G development resources on LTE," it said in a statement.

"Testing of BlackBerry 4G PlayBook models is already underway and we plan to enter labs for network certifications in the U.S. and other international markets this fall," it said.