^ Which is slightly odd as I got it (5 minutes late) on Lebara.
That is slightly odd because the emergency messaging is broadcast by the base station. Without going too technical (because I haven't worked that much on the base station side so I can't) the phone needs to be listening to the relevant time-slot when it is populated and presumably it takes several timeslot iterations (frames) to transmit the actual text.. Its repeated broadcast because it doesn't constantly listen. The handset should know its received the same thing more than once, presumably there is a message ID in there!
So you won't get it if your phone missed because:
- you are in airplane mode, the radios are disabled so phone can't hear.
- you have no signal ( wifi calling doesn't count)
- whatever Three fucked up (e.g. only transmitting once as above, or bug in some base stations)
- You had fallen back to 3G at time of the test (test was 4g/5g only)
To get it late I guess:
- the base station transmitted outside the intended window either erroneously itself, or erroneously because the trigger told it to.
- the phone has a bug and is replaying a stale message!
Its interesting to me because I workd in telecomms for so long. Most recently on 4G (LTE).
In the grand scheme of things I've lived this long without being eaten by a zombie/vampire/wearwolf, killed by a vulcano/flood/landslide and what the hell am I going to do with a nuclear warning?