Login into 192.168.121.21
Click on unified communication Manger
Click on the device drop down
Click on phone
The first drop is description the second one should be contains the last one is username.
Click on the phone you are look for.
On the left side of the screen
Click on the Line [1]
Scroll down to Call Forwarding and cell pickup setting
Under destination
In the first block put the number of the person that phone in being forward to.
DO NOT CLICK ON THE FIRST CHECK BOX UNDER VOICEMAIL.!
Click on apply config
Then ok
Click on Save.