Cell networks (but not towers) effectively do this already - when you dial 911 (or 112), the phone doesn't actually dial the number "911" or "112"; instead it r

Cell networks (but not towers) effectively do this already - when you dial 911 (or 112), the phone doesn't actually dial the number "911" or "112"; instead it requests a call of type emergency. This is routed by the mobile network itself, according to how it handles emergency calling. The phone also enters a specific "access class" (access class 10) for emergency calling mode, which lets it join other masts on networks it wouldn't normally operate on. (This is where the message "emergency calls only" originates from) But if the onward system this "un-numbered" emergency call would be passed onto is unavailable (as it sounds like is the case here) then emergency calls will fail. It might be possible to dynamically reconfigure the mobile network core , but you'd need to configure this on the core, for each and every cell tower or group of cell towers, to route the call to the right alternative lines/number. Whether that system has capacity to handle all these calls is another question.