Disable call forwarding feature Completely

[arvind.zapp]

Hi ,
I want to disable Call forwarding feature Completely.

I tried following parameters with SIP-T21P model yealink .

#!version:1.0.0.1
features.fwd.allow=0

other than above :

forward.always.enable=0
forward.busy.enable=0
forward.no_answer.enable=0

If any call forwarding feature from above three is enabled on device it wont work since features.fwd.allow is set to zero.
It works fine except one case.

If call comes to phone the user can still forward the call using fwd softkey on the display screen.

But i want to disable everything related to forwarding even the softkey should be disabled for dynamic call forwarding.

Is there a way to do this? Or is there a single parameter that can be included in configuration file to disable all features related to call forwarding?