If my experience working with AT&T in the private sector is any indication, they would be cross referencing this sort of list when establishing new access, and I doubt this is something that can be done quickly.
> ...police chief who emails AT&T requesting emergency access to prevent a suicide?
This isn't a plausible hypothetical. If it was an emergency they would be calling through established channels and the fastest way to get access to that sort of information would likely be an emergency warrant, which is easily granted in the situation you described.
It's a bit more than a plausible hypothetical. Granted it didn't involve fake police departments, but there are documented cases [0] of hackers emailing companies, including Meta, from compromised police accounts with "emergency data requests" - which are, notably, warrantless.
If my experience working with AT&T in the private sector is any indication, they would be cross referencing this sort of list when establishing new access, and I doubt this is something that can be done quickly.
> ...police chief who emails AT&T requesting emergency access to prevent a suicide?
This isn't a plausible hypothetical. If it was an emergency they would be calling through established channels and the fastest way to get access to that sort of information would likely be an emergency warrant, which is easily granted in the situation you described.