You need to talk to your mobile service provider...they control the account. If your BB PIN remains active in some other carrier BIS system, however, then no other carrier will be able to activate it on their BIS system. But, if it's actually suspended, then you do need to talk to the carrier as they are in control. If you need to ask RIM, then you need to convince your carrier to escalate your case into RIM.
That said, be aware of the reasons or suspension...BBs reported as lost or stolen are often in this condition. Further, some unscrupulous resellers will sell such a useless device to an unsuspecting customer. Hopefully this is not the case for you.
Occam's Razor nearly always applies when troubleshooting technology issues!
If anyone has been helpful to you, please show your appreciation by clicking the button inside of their post. Please click here and read, along with the threads to which it links, for helpful information to guide you as you proceed. I always recommend that you treat your BlackBerry like any other computing device, including using a regular backup schedule...click here for an article with instructions.