I just got my 8700c yesterday, on Cingular, and I am trying to install the BlackBerry Messenger software on the phone. I also have the BB Personal Unlimited data plan.
I have come into many problems trying to install the software. I have the Latest Desktop software, and I've also updated the handheld software to the latest version.
Everytime I have the BB connected to my laptop, and I try to go to the blackberry.com/messenger website, it says either "An Unknown error has occurred." or "Blackberry Device not found" when it is clearly connected, as the BB Device Manager can see it fine.
I've also tried to go to the website via the BlackBerry handheld itself, but it just comes up with the error "The requested page can not be displayed" and that's it..
Is there something i'm doing wrong or a setting I might need to change to get this application installed? Is there somewhere I can download it to the Desktop and then install it via the App loader?
Do you have a "Blackberry Data Plan?" Edit: I see that you do from all your other posts. So, go to Options >Advanced Options >Browser. Set default broswer configuration to Internet Browser (or Cingular Browser with Cingular I think). Save settings. Then try the website again.
FYI I was able to finally get it to work by browsing to it from my BES browser, NOT the standard "Internet Browser." You might try something similar (the carrier browser if you are on BIS or BES browser if you are on BES) and it may help.