This post describes how to configure direct tranfer of calls to a person's voicemail. So without ringing that person's extension and without going through the opening greetings. Believe me, receptionists love this!
First of all, create a separate voicemail profile for this purpose, using the existing VM pilot (5999 in this case):
Secondly, add a CTI Route Point:
CTI Route point
will never register, and is only used for its CFWD ALL settings.
Now configure the pattern that you require for direct transfers to voicemail, in this particular case, 4 digit internal extensions are used, using a * as prefix and add it to line  of that
point. Set Call Forward all, to Voice mail.
Now, in this example I have chosen *XXXX as the pattern for direct transfers, this means for instance that if someone forwards a call to *1122, this call will be forwarded to the Voicemail box of the user with extension 1122. This is where receptionists go "Mrs. Doe is not in, but i can transfer you to her voicemail so you can leave a message".
This is also a great feature when used in conjunction with Hunt pilot forward setting, where you can easily set the Forward Hunt no Answer and Busy settings to transfer to voice mail. In the example below, hunt pilot 7500 is forwarded to its voice mail box once hunting is exhausted: