I’m not an expert in the modern comms protocols but I gather that ability was lost when the mobile protocols became packet-switched data-only protocols.
3G and below were “circuit switched” and internally made temporary “circuit” connections for calls. With the dedicated part of the protocol for making voice calls, any calls to 000 could be identified directly on the network and routed by them regardless of subscriber. LTE and later protocols only deliver data as IP packets, and no other special payloads, and do not keep track of connection/circuit state. On 4G+ voice “calls” are Voice over IP, sent as data packets on the network and treated the same as other data packets.
For the 4G or later networks to handle 000 calls especially, it has to let everyone connect to allow a locked down type of data roaming, and allow that roaming to only connect to the Voice over IP for 000. Which is entirely technically feasible, just requires more effort from the networks.
I’m not an expert in the modern comms protocols but I gather that ability was lost when the mobile protocols became packet-switched data-only protocols.
3G and below were “circuit switched” and internally made temporary “circuit” connections for calls. With the dedicated part of the protocol for making voice calls, any calls to 000 could be identified directly on the network and routed by them regardless of subscriber. LTE and later protocols only deliver data as IP packets, and no other special payloads, and do not keep track of connection/circuit state. On 4G+ voice “calls” are Voice over IP, sent as data packets on the network and treated the same as other data packets.
For the 4G or later networks to handle 000 calls especially, it has to let everyone connect to allow a locked down type of data roaming, and allow that roaming to only connect to the Voice over IP for 000. Which is entirely technically feasible, just requires more effort from the networks.