like there should be a workaround/hack that then let’s you place any kinda call for free.
In: 3640
When I was a 911 operator (about 9 years ago), people’s cell phones without a SIM would often malfunction (or perhaps pocket dial) and call 911 repeatedly. I’m talking about 300 calls a day to 911. And you’d just hear pocket rustling or just dead air.
There was no subscriber info or phone number to call back. Really frustrating.
When I was a 911 operator (about 9 years ago), people’s cell phones without a SIM would often malfunction (or perhaps pocket dial) and call 911 repeatedly. I’m talking about 300 calls a day to 911. And you’d just hear pocket rustling or just dead air.
There was no subscriber info or phone number to call back. Really frustrating.
I know its most likely answered, the GSM emergency number, 112.
The number is carrier independent, and towers are programmed to take the call, no questions asked. In times where a tower is operating at maximum capacity due to number of phones connected (say a sporting event nearby), a tower will actually drop active calls to take an emergency call.
I dont know about other countries, but in Australia, 112 *OR* 000 (Australia’s emergency number) will work. It would not surprise me if they programmed 911 for the American Tourists, and 999 for the British tourists 🙂
I know its most likely answered, the GSM emergency number, 112.
The number is carrier independent, and towers are programmed to take the call, no questions asked. In times where a tower is operating at maximum capacity due to number of phones connected (say a sporting event nearby), a tower will actually drop active calls to take an emergency call.
I dont know about other countries, but in Australia, 112 *OR* 000 (Australia’s emergency number) will work. It would not surprise me if they programmed 911 for the American Tourists, and 999 for the British tourists 🙂
A Sim card is kind of like an ID badge. It tells the security guards which rooms you’re allowed to use.
But the guards also have instruction to let anyone use the 911 room, even if they don’t have a badge.
So the only way to “hack” it would be to change something in the cell towers themselves, not your phone.
A Sim card is kind of like an ID badge. It tells the security guards which rooms you’re allowed to use.
But the guards also have instruction to let anyone use the 911 room, even if they don’t have a badge.
So the only way to “hack” it would be to change something in the cell towers themselves, not your phone.
I gotchu and I can answer with authority because I’ve actually written the embedded software that makes emergency phone calls.
Disclaimer: this is not an advice on what you should do during an emergency. Do what your local government authority recommends and figure out the right number to call.
[My top voted comment](https://www.reddit.com/r/explainlikeimfive/comments/7mb35n/-/drsxmdn) is an answer to a similar question. Feel free to look it up.
As others have said a SIM card is there to identify your phone to the network and to optimize how your phone searchs for service.
So if you are a T-Mobile customer, an AT&T cell tower won’t let you use their service/tower.
Also, say T-Mobile only uses radio frequency bands 1, 2 and 3 (I’m simplifying it here) and AT&T uses bands 4 and 5 in your region. If you are a T-Mobile customer, there’s no point in having your cellphone jump onto Band 5 and say “hey, I’m here! Can any cell tower hear me?”. It’s a waste of time and more importantly your battery.
But when you don’t have a SIM card or you have a T-Mobile one and your phone searches bands 1, 2 and 3 and finds no T-Mobile service, it starts searching other bands (in case you’ll need to make an emergency phone call in the future) and registers with whatever cell tower has the best signal and can actually support voice calls (for example some cell towers or bands mught be only for data).
And when you make an emergency call, the number doesn’t even matter really. In the protocol for making calls (think cool handshake between phone and cell tower) there’s a signal to say it’s an emergency call. The tower sees it is an emergency call, prioritizes you over Karen calling wanting to talk to the manager, disconnects her and puts you through (I gotchu buddy).
It doesn’t even care what number you called because it’ll have to route you to a different 911 call center based on your location anyway. IIRC (it’s been a long while) I don’t think we even send out the phone number you called when it’s an emergency call. Phones have a common list of emergency numbers and it’ll connect you to emergency services even if you dial 911 in Europe even though the actual emergency call number in Europe is 112.
Depending on your phone’s capabilities (most phones these days) it’ll even automatically start doing a GPS fix and then send it out when it has your location.
So yeah, you aren’t going to be able to hack anything in the emergency call protocol to make free calls.
I gotchu and I can answer with authority because I’ve actually written the embedded software that makes emergency phone calls.
Disclaimer: this is not an advice on what you should do during an emergency. Do what your local government authority recommends and figure out the right number to call.
[My top voted comment](https://www.reddit.com/r/explainlikeimfive/comments/7mb35n/-/drsxmdn) is an answer to a similar question. Feel free to look it up.
As others have said a SIM card is there to identify your phone to the network and to optimize how your phone searchs for service.
So if you are a T-Mobile customer, an AT&T cell tower won’t let you use their service/tower.
Also, say T-Mobile only uses radio frequency bands 1, 2 and 3 (I’m simplifying it here) and AT&T uses bands 4 and 5 in your region. If you are a T-Mobile customer, there’s no point in having your cellphone jump onto Band 5 and say “hey, I’m here! Can any cell tower hear me?”. It’s a waste of time and more importantly your battery.
But when you don’t have a SIM card or you have a T-Mobile one and your phone searches bands 1, 2 and 3 and finds no T-Mobile service, it starts searching other bands (in case you’ll need to make an emergency phone call in the future) and registers with whatever cell tower has the best signal and can actually support voice calls (for example some cell towers or bands mught be only for data).
And when you make an emergency call, the number doesn’t even matter really. In the protocol for making calls (think cool handshake between phone and cell tower) there’s a signal to say it’s an emergency call. The tower sees it is an emergency call, prioritizes you over Karen calling wanting to talk to the manager, disconnects her and puts you through (I gotchu buddy).
It doesn’t even care what number you called because it’ll have to route you to a different 911 call center based on your location anyway. IIRC (it’s been a long while) I don’t think we even send out the phone number you called when it’s an emergency call. Phones have a common list of emergency numbers and it’ll connect you to emergency services even if you dial 911 in Europe even though the actual emergency call number in Europe is 112.
Depending on your phone’s capabilities (most phones these days) it’ll even automatically start doing a GPS fix and then send it out when it has your location.
So yeah, you aren’t going to be able to hack anything in the emergency call protocol to make free calls.
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