Is it possible to unlock a wireless receiver which act as a modem?

[therohitdevil]

My network setup is such that a Outdoor wireless CPE receives signal froma nearby tower to provide Internet. This Cpe is connected to my Router using RJ45 Connection. I cant access the firmware of outdoor CPE. I guess the default gateway has been changed by the ISP. Is it possible to access the firmware of the CPE?
The example of CPE can be taken as Nanostaion LOCO.

 

[humangod]

have you been able to access the CPE before?