Can I place emergency calls on a FirstNet cell with a standard cell phone?

Question

Recently I was part of a wilderness SAR training event where there were drone-based FirstNet cell tower deployed to provide emergency personnel with cellular communications in remote areas.

Perhaps I am the lost hiker that is being search for in this scenario, would I be able to place an emergency call through this network?

Would emergency services be able to detect my "ping" (assuming I had a GSM phone) without a FirstNet SIM?

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FirstNet is a federally supported USA based national emergency cellular network (segregated network) provided by AT&T and is GSM based, the drone deployment was being tested for SAR use in remote areas.

This question comes from me noticing that my personal phone did not have any indication of service, although I did not explicitly place a 911 call to test an emergency, but the FirstNet device had full bars and had all your usual 4G services available.

[This is explicitly about the USA, but answers related to other areas with similar emergency cell network arrangements are ok too]

Answer 1

I have no certainty in this answer, so it may be inaccurate.

The idea behind FirstNet is that it allows priority for emergency services in times of emergency. In several (relatively) recent disasters such as the attacks on 911 and during hurricane Katrina, regular phone services were overwhelmed by emergency and non-emergency calls, so a dedicated priority network was decided upon to overcome this problem.

I suspect that with a regular phone you would be unable to place an emergency call over this network, as it needs an activated phone with the right capabilities. Some of the latest phones are deemed FirstNet capable (Samsung link about FirstNet).

However, this link indicates that the money it costs the utility providers is, at least in part, defrayed by allowing the bandwith to be used by regular users outside of a local emergency, so there is the potential that the network is available to regular users at certain times, just not when an emergency is happening.

It also seems that under certain circumstances, such as a failure of the primary emergency network, 911 calls will be routed through FirstNet - note that you don't get to decide this, and nor does your phone, it is a decision made via the computers that run the networks. Here's what AT&T have to say about it:

If AT&T ESInet detects a failure in the primary connection to the PSAP, emergency calls will be automatically routed over FirstNet. (from the link above)

My interpretation of this is that the ESInet receives the call, but can't place it, and so routes it through FirstNet - so it's not your phone connecting to FirstNet, hence my thoughts that you can not make an emergency call through this network.