The geeks over at StreakSmart have posted up a video and some photos of the Streak 7 hidden call function they dug up. Before you get too excited, the call function isn't prominently placed for good reason - it doesn’t work.
The geeks found the call function by tapping the bar below the keyboard to get the dialer with icons for tablet, call log, contacts, and favorites to pop up. You can input phone numbers and the call will try to dial.
Apparently, the calls fail and things just don't work. Imagine that, calls won't work on a device never meant to have that function. Still, I wonder if the dialer being present indicates that calls could be made to work with hacks or an update from Dell. It's more likely to be a function that just wasn't remove from the OS when Dell built the tablets. You can pick the Streak 7 up on T-Mo right now.