Everyone must have a callgroup.
As an example three locations, downstairs, ground floor and upstairs.
Assign a callgroup to each such as 1 to downstairs, 2 to ground floor and 3 to upstairs.
Then in pickupgroup on each extension define which group *8 will pick up for. So any phone in the basement should have pickup group 1 in the extension profile. If you want when your in the basement to pickup a phone ringing on the ground floor (since you can hear it) you must also give the extensions in the basement the pickup group 2 so they would have 1 & 2 as the pickup groups.
On the ground floor, you may be able to hear the basement and upstairs so you may want to pick up all three groups with *8 so put in 1,2 & 3 in pickup groups.
Basically call groups seperate departments or divisions and pickup groups allow a user to pick up or intercept a ringing call from the groups they are allowed to pick up.
