Cannot upgrade the speed of the PVC

[kradjesh13]

One of our sites speed is upgraded to 2M/384K from 215/64K. I have been trying to update the speed and its not allowing me. But i have configured brand new routers with 384 without issues. Hope some one can help me out.

interface ATM0.1 point-to-point

Router(config-subif)#pvc 8/35

Router(config-if-atm-vc)#ubr 384

When i change from 64 to 384 i am getting the following message

% Invalid input detected at '^' marker.

Its cisco 877 router with c870-advsecurityk9-mz.124-4.T7.

Thanks

Rajesh

[kradjesh13]

Also wondering this issue is because of the line sync speed ??? I guess if i reboot the router i can able to change the speed.