The most elegant way to set this up is with a coverage answer group.
You start with an X port station. This extension will be what users call when trying to reach the help desk.
Create a call answer group (add cov ans next). Add the 4 stations to this group and note the group number.
Create a coverage path for this coverage answer group (add cov path next). In the first point of coverage, put CX (X= the coverage answer group number). The second point can be voice mail, or just about anything you wish. Note the coverage path number and save the form.
Change the x ported station (ch st XXXX) and add the coverage path to the station form.
Now when someone dials your lead extension, the call will ring on all 4 phones simultaneously, then it will move on to the next point of coverage (I would use a centralized voice mailbox for your X ported station).
Good Luck