Adding onto this, I'm reading Three didn't broadcast for the 20 minutes but rather only broadcasted once at 3pm which is why only a minority of users on Three received the alert.
As @Bletchleyite says, emergency broadcast messages are exactly that - broadcast - meaning that any phone that's in range and connected to the network will receive it. So it makes no difference if there's one or one hundred thousand phones connected to the cell.
It doesn't require a data connection. AIUI, it uses the standard SMS infrastructure so just depends on the phone being registered on the cellular network at the time.
No data connection is required. The reason the phone has to be 4G or 5G is because the previous standards didn't include the emergency broadcast facility.
Would imagine that is the case as had a genuine one in Romania a couple of weeks ago.
Smarty is, I believe, on the Three network, so that may partly explain why you didn't receive it.
Likewise LG G6 2018
My first thought was. If there is a sword wielding nutter within a few hundred yards of me then maybe I could move further away. BUT then in which direction do I choose to move ?. Is this just going to cause unnecessary panic, curiosity or confusion ?. How big an area does it cover ?. I suppose a gas attack on the tube might encourage me to get up to street level - but what network works down there ?.
One scenario I can think of is a river that's on the verge bursting its banks - you might well be aware of the fact that it's been raining a lot, but not necessarily know when it actually happens.
For example I know my relatives living close to the river Taff in Cardiff get warnings. The disadvantage is they had to subscribe to them and most don't bother. I was the first to subscribe (though I am hardly there). But the trouble with the flood warnings is too many warnings so they now ignore them and remind me it was my fault I encouraged them to register !. Reminds me of "the boy who cried wolf" story. Lets hope the government do not overdo the use of this.
Hopefully so. If ministers are true to their word, most people will never receive an actual alert.
I don't believe that anyone responsible for sending these alerts will be able to send them in anything like as time-critical a manner as you imply - you'll be told that there's a "danger" of a river bursting its banks (perhaps) but not an alert at the time it's about to happen. Just think how long it took them to attempt to send out a generic message yesterday, and even didn't manage to do this.
I think that's the point. There are cases in which it could be life-saving, and if your view is that any information is better than none at all, then this is good. It also enables the "something must be done" and the "we have done something good" parties to be happy. And I don't have a problem with that approach.
In 1996 I was sitting outside in Wilmslow with my parents, temporarily living with them before buying a place of my own in Manchester, and I was planning on going into Manchester to see my friend who was a train driver. From memory, he either called or texted me not to bother because the train he was driving towards Piccadilly was stopped and clearly not going anywhere for a while, something was "up". I don't know if the alert system today would be designed to tell people 10 miles away of something as significant as the IRA bomb, but even if it was I got timely and important information from other means anyway. But it might have helped you, I admit.
As noted above, it isn't sent to specific phone numbers but to all phones registered in the specific cell(s) where the alert is triggered. This will include phones that are roaming on a 'foreign' network at the time.
