Are you talking about paging over the loudspeakers or calling a specific phone like an intercom? The latter I don't know specifically but I could figure it out if needed, but paging over the loudspeakers is done by hitting the button labeled "Page Speaker" or its equivalent.
Well, you don't. Tie a piece of string between two (empty) soup cans, one on your end, the other to the person you're trying to reach. Then yell real loud, " HELLO???"
Why would you not want them to pick up their receiver? You can press the speaker icon on your phone if you don't want to pick up the receiver but the person on the other end of the line has to do the same thing if they wish to use the speaker function too.
There should be a slide out card on the phone that explains all the functions. My favorite function is the transfer button. Being in the bakery department we get everyone else's phone calls because the people calling don't wait to listen to the whole menu and bakery just happens to be first alphabetically.