Add the option to transfer calls directly to voicemail on Unify CPXXX phones.

Currently most other phones that RC sells allow the option to transfer a call directly to a user's voicemail. Can we please get this support for the unify phones? This is an important feature that is used w/ presence at our company. We need to know if someone is on the phone and if we have to send a call to them or directly to VM. This feature would allow for much better workflow and better client retention within our company.