I just tried with the one on the floor, and YES the Sony P can send and receive text messages. I sent a message to my work phone, and it went just fine, as did my reply back to it. Now, I don't know if this is because of the company SIM inside allowing it whereas normal customers won't be able to, but the hardware did it just fine. Calls to the number, though, just came up with the disconnected sound. But SMS was fine.
On a side note, though, the thing is really not that great. The screens are ok, at best, but the dual screen setup just makes more issues than it solves. Web browsing is awkward, some apps only use one screen, the PlayStation usage is just not good due to the on-screen controls, and the speaker is atrocious. It works pretty good for watching video, as it uses the top screen for the video, and shows the controls on the lower screen. And it has a quick-button to send video via DLNA to a TV. All-in-all, though, it just just too funky for its own good. Especially at the price.