CoS (Class of Service) is a designation in E9‑1‑1 that defines the service category of the telephony service. A few examples are residential, business, Centrex, coin, PBX, VoIP and wireless Phase II (WPH2).
VoIP Class of Service sold as not having nomadic capability. Refers to an IP end-point that cannot move, is always in same location and always accesses a network from the same point.
FX (Foreign Exchange) Service
A telephone line switched in an exchange or central office other than the exchange or central office area in which the telephone is located.
Relevant NENA Documents