[blocking_io]

You have always been able to deny calls using the power button on top. Presumably that method is now compulsory.

[baudehlo]

That doesn't deny the call. It just turns the ringer/buzzer off until they give up.

[parasubvert]

If you double click the top button, it does deny the call.

[shurcooL]

You can press it a second time after that to "deny" the call.

[ajanuary]

Pressing it again will deny the call.