John McAfee, libertarian politician and former computer programmer, tweeted this:
The "Presidential alerts": they are capable of accessing the E911 chip
in your phones - giving them full access to your location, microphone,
camera and every function of your phone. This not a rant, this is from
me, still one of the leading cybersecurity experts. Wake up people!
Leading cybersecurity expert status aside, is any of this based in reality? Could the Presidential Alerts system give any government agency, body, or official, any level of control over cellular devices beyond sending alerts?
The presidential alerts are part of a bigger system that also includes AMBER alerts and alerts for bad weather and "other threatening emergencies". These alerts are called Wireless Emergency Alerts (WEA).
No. Just like emergency weather alerts you see on local TV, WEAs are broadcast from area cell towers to mobile devices in the area. Every WEA-capable phone within range receives the message, just like TV that shows the emergency weather alert. WEA, like the TV station, doesn't know exactly who is tuned in.
The FCC also says "WEA is not designed to – and does not – track the location of anyone receiving a WEA alert". Verizon Wireless says something to the same extent.
If you're on a phone call, the message will wait until you're done (you won't get a message if you get off when the message is no longer being broadcasted), but I see no evidence this is done by the broadcaster. It seems far more likely that it's the phone itself that does this.
This isn't a complete answer to your questions, but I'd like to point out that the government doesn't need access to the E911 chip to locate you. Traditionally mobile phone networks were switched networks. They work by locating where you are in the world, and routing your telecoms through a microcell / macrocell transmitter.
It's been some time since i worked in telecoms, some of this might have changed now and I've forgotten some of it, but this is how it used to work.
Each cell transmitter has a fixed number of channels much like a television has. Once the channels are all in use, no further calls can be placed through that cell. Although, there may be special provisions for emergencies like police and ambulance calls.
Due to the limited number of channels each cell has and the very limited broadcasting range of a cell, it's necessary to work out your position accurately. This is done periodically by a regular update that notifies the nearest cell where you phone is. The cell sends back the information to a central database, for the mobile phone provider. They store all this information in a database called a HLR (home location register). This keeps accurate information of where you are to within a few hundred meters if your phone has the battery installed.
So essentially, mobile phones always were personalized tracking devices since day one. Not necessarily because they were meant to be, but because of the way the networks functioned. So the government absolutely can find out where you are at any time, if you take your phone with you. They don't need an E911 to do this.
I should also point out that there's something now called a VLR, which suppliments the HLR's functionality.
Description of the Ericsson HLR. I can't find a public description for the HLR at Nokia where i used to work.