You can add members to a pickup group to allow any member of that group to 'pickup a call'
For instance, if there is a member of your team off for any reason, and their extension is ringing, you can intercept the call and answer it.
The first screen you see lets you know how many members there are for each group.
If you click on a group name, you can see the members of the group, which site, and what type of call they group is for.
To add members to a group, double click the CHANGE button, select the user you want to add and press the < butting in the centre.
Once you have finished making changes, click SAVE.
The PICKUP button can now be used as above.