I've got an iPhone 3GS which is jailbroken and unlocked. I got it that way from a trade lately and for some reason I simply can't get push notifications. The weather won't update automagically, nothing. I get email from my Exchange account but that's it.
The phone was probably hackivate which usually cause push issue. Did you google and tried all the push tweaks? The other and best option is to get you hands on the official carrier sim, even none active one will work. Afterward, put the sim in the phone. Create a custom firmware file, with options that don't change the baseaband and not activate the phone, with Pwnagetool(Mac) or Snowbreeze(Windows). Use Redsnow (Windows) or Pwnagetool to put the phone into a special DFU mode, restore with the custom firmware through iTunes and activate the phone. Then, install Ultrasnow if you need to unlock the phone.
