I don't know any way to retrieve messages that were blocked. I performed a google search using the string "unblock text messages" and found one other person asking your question. No one answered it.
SMS, no. There is no record of it unless your mobile carrier keeps them. PIN,, I am sure RIM keeps these for legal matters and will produce as the result of court subpoena.
I don't know that that's a RIM decision. If you think about the volume of text messages, it seems like it would be impractical for a carrier to keep them. See this link, for example: Cellular Phones: text content, storage space, text messages
There is no reason at all for RIM to be the least bit interested in keeping data that does not flow through it's servers. As for the carriers, they are obligated to retain a certain a timeline for legal purposes, but they are under no obligation to provide a copy of the SMS without court order.
That's right, considering that SMS is not data (therefore, RIM has nothing to do with it). It's mobile to mobile calling which is why it's billed differently. Only the carrier keeps that list of what comes to your phone, and leaves from it.
The carrier will have the list of all incoming and outgoing SMS numbers on your bill. Just like the list of regular phone calls. Including the ones your phone is supposed to block. That's because an incoming SMS still goes through the carrier (and gets counted) on its way to the phone before getting blocked by the OS where only you won't see it . Your bill won't have what the text was though. That is where getting court orders comes in.
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