Find out Firmware and Baseband iPhone 4

Hello there,
I recently bought a locked iPhone 4. Because I don't have a fitting Sim, I unfortunately cannot find out the firmware and baseband via the settings anymore. Dialing the special number *3001#12345#* doesn't work with the iPhone 4 neither.
Does someone have a hint how else I could find out the firmware and bootrom?

Thanks!

Thanks for the quick reply!