Can I sell my motorola nvg510 u-verse equipment if i paid 100.00 when I got it?

I purchased a Motorola nvg510 u-verse. I paid 100.00 for it.
later I moved to another address where ATT was not able to service U-verse.
I ended getting cable Internet service.
now I have 8 months old Motorola nvg510 u-verse which i like to sale.