Are you talking about "transferring" a call or picking up a night bell?
To transfer, meaning someone has answered the call and then sends it to another, you do it exactly the same way you transfer to any other phone.
To pick up the night bell, you need to look up your "Trunk Answer From any Station" (TFAS) code in the feature access code assignment form.
Then when the night bell is ringing you dial that code.
Ralph
www.university-music-on-hold.com