For the second time this year as many as 50% of all BlackBerry users on all North American carriers are experiencing an outage. More specifically, they are experiencing a BlackBerry Internet Service (BIS) outage.

T-Mobile and AT&T have confirmed that their BlackBerry users are affected and, although we haven’t had a confirmation from the other carriers, dozens of BlackBerry users on Sprint, Verizon, and even Alltell are reporting that they aren’t getting their email.

It hasn’t been officially determined if the BlackBerry outage is on the side of the carriers or RIM. The fact, however, that all carriers seem to be affected would lead one to speculate that the issue is with RIM. This doesn’t bode well because when this happened, not even five months ago, RIM said that it wouldn’t happen again.