sbg901 can't access the modem's gui. Possibly blocked?

Hey guys,
I have a sbg901 that seems to be locked by my ISP.  I cannot access the modem's configuration page.  (192.168.100.1) It is the default gateway.
Is there a way around this?
Will installing an updated firmware change this?  I suppose that if I were to get my hands on a different version of the firmware, my ISP would update the firmware and I would be locked out of the modem's gui again.

Any help would be greatly appreciated.

Cheers,