Root I need original firmware, please

[chemono]

i have a tablet 7 inch wm8650, lately i used uberoid to change it, but itis not working properly, the problem is that the tablet has gsm built (sim slot) in but until now i haven't found a rom that suport call. that is why i want the original fimware but i still not found it, someone please help me!

- CPU VIA8650, 800MHZ CPU
- with SIM Slot
- Mini USB
- Black Color Audio Jack
- TF Slot
- USB Slot
Green Light when ON, Red Light when charging.