Sony has filed a patent for a cellphone attachment to their PlayStation Portable handheld systems.
“In two filings dated November 10, 2004 (and made public in late February 2006 and only three days ago, respectively), a gaggle of Sony designers submitted applications for both “ornamental design[s]” for a keyboard and phone add-on for the PSP.”
Quote from PSP keyboard and cellphone attachments on USPTO
The attachment looks a bit awkward. I see no reason why I would attach a cell phone to a PSP, except maybe to provide wireless connectivity from anywhere in order to send email.