we have installed 12 port emtas and 8 port emtas at the same location. Generally works fine with pbx/key system with an opx. Arris makes the emta. Will not work for ground start systems that I have seen. We run an 8 port at our office with a NEC system and experienced no down time.
This is CABL.com posting #230068. Tiny Link: cabl.co/m70W