I want to take my Blackberry 7280 from the Rogers the the Telus Network. Is it possible. I think you can just mod the firmware possibly. I have a SIM card already and it fits just when you turn it on it says "Invalid SIM card." Can you make it work? (I don't care if i void my warranty)

You can't do it.
Telus is not a GSM network like Rogers is. The two networks are not compatible with eachother.