N90 TRACON Controller reported they received no briefing or notification that keypad entries for making handoffs changed due to an airspace reconfiguration.

Narrative

I am absolutely dumbfounded. I arrived today for my shift at N90 LGA sector. This is my first shift with the EWR airspace being in PHL Tracon. I have received ONE very short; verbal briefing from the FAA. That briefing was only in regard to the RDVS communications panel. Otherwise; I have received no communication from the FAA. I have been told by my NATCA reps that the FAA has said 'nothing will change. It will be status quo'. Well; this morning I found out that something significant has changed. My keypack entries for handoffs to the EWR area are no longer '4' and then the position #. Now; we have to handoff to '9' and then the position #. For example; If I want to hand off to EWR Dept; I need to type '9N' instead of '4N'. Given the speed at which we have learned to type and muscle memory that has been developed; this IS a significant change and should have been briefed before controllers took the position. During a very busy session; this could absolutely result in a controller failing to input a handoff in a timely manner. The FAA should be utterly ashamed of themselves for failing to properly brief controllers about this change. They took a position that essentially said 'nothing is changing' so that they could accomplish the move with as little resistance as possible. Make no mistake; this is a major change. Not having the EWR controllers in the same room as us is a significant detriment to safety and efficiency.