If you're an active mobile phone user, you will notice that your phone can actually make emergency calls without any SIM. I know you must be wondering how this is possible since there's no mobile number. Let me explain how your SIM works. SIM as you ought to know stands for Subscriber Identification Module and it helps to identify the cell service subscriber that is trying to connect to the network. Every user has their own SIM, so network providers can direct calls to that specific phone and track usage (and charges) individually. The identifying number of a SIM card is called an ICCID.
The IMEI is like the DNA of a phone; all phones can be identified just with their IMEI. This is a logical example of what happens when you call your friend with a SIM card:
Michael’s phone to cell tower : My IMEI is 123 and my ICCID is 456. I want to call +234-123–456–7890, please!
Cell tower: IMEI is 123, ICCID is 456; 456 is Michael’s account. I’m from Michael’s cell phone carrier and provide him with service, Michael has 100 minutes left in account, connecting call.
Michael : Thanks!
Now This is what happens when you try to call a friend without a SIM card:
Ade’s phone to nearby cell towers: My IMEI is 123 and I don’t have any SIM card. Please let me call +234-123–456–7890, please!
Cell Tower: Who's this one again ? Are you normal? You didn't even subscribe to any services, or even my own network ; why should I give them to you for free? Gerrarahia Mehnn!
Ade : Chai!
That sounds quite interesting, right? In the first instance, the cell tower allowed Michael to place the call because it knew who he was and that he was paying for it, but in the second, Ade was unsuccessful in placing the call because the tower had no idea who it was and didn’t want him using the service for free. It's like allowing a total stranger into your home.
Now what if the person on the other side of the door was involved in a terrible accident , on fire, or getting robbed ? What would the cell tower do?
Musa calling 911 or 112 with SIM card:
Musa’s phone to cell tower: Help Musa is dying! My IMEI is 123, my ICCID is 456, my latest location is 123 Musa’s Place, please connect to emergency services!
Cell tower: I can see Musa’s info with ICCID #456 and your latitude and longitude coordinates, connecting to Emergency Number!
Musa : Help, I’m on fire!
As you can see, 911 was able to receive information about Musa thanks to his ICCID and GPS coordinates.
Rochas calling 911 without a SIM card:
Rochas' phone to all nearby cell towers: Hello, please anybody around , help! Rochas is on fire!
Nearby cell tower: I’ll take the call! I really don’t care who you are, but I’m willing to help! Your IMEI is 123, meaning that you’re a Black variant of the Tecno Phantom 8, and your location is 123 Rochas’ Place! Connecting to Emergency number because I’m nice and I don’t want you to die yet !
Rochas : Help oh ! Rochas still got the help he needed, even with no SIM card. The emergency services would’ve been unable to receive much detailed personal information on John, but they knew his location and would be able to get there quick.
To round it up, cell phone towers are a lot more like paranoid kids staying at home for the first time. They won’t let you in if you don’t know their “secret password” lol, but are kindhearted enough to accept your pleas to help no matter who you are. So next time you’re in an emergency, don’t let “no service” fool you.