Technically only the not yet functional DMS-10 is digital, everything else is analog. The 3ESS is a stored program, computer controlled analog switch - it uses

Technically only the not yet functional DMS-10 is digital, everything else is analog. The 3ESS is a stored program, computer controlled analog switch - it uses the same remreed technology the 1AESS used to set up call links. Out of all of those however, panel is my favorite however, it sounds amazing to listen to, both the equipment and what the line sounds like. A call between a panel and the number 1 xbar sounds amazing, nothing quite sounds like revertive pulse signaling. Interestingly enough, there were three switches made that used RP internally - Panel, 7A Rotary and 1XBAR - and if you go find video of the 7A Rotary, you'll see it sounds almost exactly like panel, because the unique sounds of the rotary sequence switches both exchanges use.