Another thing to consider is how many development resources a given product/team has available. Emergency Responder is fundamentally a supporting product[0] to

Another thing to consider is how many development resources a given product/team has available. Emergency Responder is fundamentally a supporting product[0] to their PBX software. For the organizations that need it, it is something they have to have, but nobody that buys PBXes[1] picks a PBX on the basis of the security of the E911 add on package. Now, if you're a big vendor, do you give more resources to the PBX team that builds features which sells PBX customers, or the add on team used by a fraction of a percent of the worldwide PBX install base? I'm not asking what you should do, but rather what your inner MBA would do... 0 - the fundamental purposes of Emergency Responder are to a) provide enhanced location information about a caller, say the general location within a building, and b) to allow emergency responders to call back the person who placed an emergency call, even if the phone they called from does not have a directly callable phone number. It does some other things, too, but those are the "primary" features. 1 - source: sold a whole bunch of PBXes.