While Avaya and others have always had a “hunt group list” that gets the numbers programmed, Nortel was very late to that party. For years we would simply set up the first (pilot) number on a phone that has FDN set to the second number and SFA in the CLS. The second number would be on the second phone, with FDN set to the third number. The third number would appear on all 9 phones as MCR instead of SCR. It was that simple. You can still do it that way, but you have a second alternative if you choose to use it.
With later software, you have the option to set up the hunt group in overlay 18 just like you program a speed call list, with the three numbers programmed in the first 3 bins and program the pilot number and phones accordingly. The pilot number is programmed as GPHT in overlay 57, pointing to the SCL you programmed in overlay 18. When callers dial the pilot number, the programming supersedes any hunting programmed on the phones.