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I found out today that ISPs get the IMEI code of any device connected to them.

See a (very old) reference here: http://news.bbc.co.uk/2/hi/technology/4738219.stm

I was hence wondering: in case I connect to the web through a mobile hotspot with a prepay SIM card, which IMEI(s) does the ISP gets?

Say the setup is: Laptop - mobile phone - internet

Does the ISP get only the mobile phone IMEI, the laptop IMEI or both?

Astarte
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  • Laptops typically do not have an IMEI (unless they can connect to the providers data network themselves). Is this such a kind of Laptop you use? – Marcel Apr 28 '20 at 05:00
  • Do you mean that the connection via hot spot is *the only* connection to Internet? Or you have both simultaneously - some hosts directly via laptop SIM, the others via hot spot? – mentallurg Apr 28 '20 at 12:59
  • I meant that the connection via hotspot is the ONLY onncection. I probably confuses you mentioning a laptop IMEI, but Angel is right in his answer: I really meant the MAC address of the laptop, or anything that would make the laptop identifiable in any way. Imagine I'm using the laptop with a mobile phone and a SIM, and after a while I use the same laptop with another mobile phone and another SIM. Will the carrier be able to tell it's the same laptop? – Astarte May 20 '20 at 23:45

2 Answers2

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The phone company will receive the IMEI of the mobile phone, which is the device connecting to them. You might have one, zero or dozens of laptops behind that phone. Not to mention, laptops don't have IMEI codes (the equivalent would be the MAC of the Wifi card)

Ángel
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    You are not correct regarding laptops. If laptop has its own SIM, then of course it has its own IMEI. – mentallurg Apr 26 '20 at 03:34
  • And the Mac of the laptop WiFi does not propogate as part of the IP traffic out of the Hotspot. @mentallurg - A laptop SIM, even if present, would not come into play through an external Hotspot connection. – user10216038 Apr 28 '20 at 00:44
  • @user10216038: I don't understand what you mean by *A laptop SIM ... through an external Hotspot*. But in case laptop has own SIM card it has at least 2 network interfaces and can establish at least **2 independent** Internet connections: one via own SIM card and one via mobile hot spot (and thus another SIM). Thus the ISP (or ISPs if SIM cards are from different ISPs) **can** see 2 different IMEIs. EMEI of the laptop own SIM and EMEI of hot spot SIM. You can configure routing on laptop so that host A is reachable via one interface (own SIM) and host B reachable via hot spot (another SIM). – mentallurg Apr 28 '20 at 02:55
  • @mentallurg The question said "in case I connect to the web through a mobile hotspot with a prepay SIM card". And "Say the setup is: Laptop - mobile phone - internet". So it is not connecting through the laptop SIM, even if there is one. For the question that is being asked, the correct answer is the IMEI of the mobile phone. – auspicious99 Apr 28 '20 at 04:13
  • @auspicious99: May be you are right. But it is not said that this is *the only* Internet connection. We should not guess, but ask the author :) – mentallurg Apr 28 '20 at 12:58
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TLDR: It depends on your routing configuration.

You should check how routing is configured on your laptop.

1) In case you forward all traffic to the hot spot, the ISP (of the hot spot SIM) will see the IMEI of the hot spot SIM. The ISP of laptop SIM will not see anything, because you don't use laptop SIM.

2) You can also configure routing on your laptop so that traffic to some hosts is routed via your laptop SIM and traffic to some hosts routed via hot spot. Then the ISP of laptop SIM will see your IMEI when you access host A and the ISP of the hot spot SIM will see the IMEI of hot spot SIM when you access host B.

What should you do if you are worried? Check routing configuration on your laptop. If both network interfaces are active, you will see that your have 2 different IPs, 2 different network gateways, different DNS servers for each interface etc. Then adjust routing as you need.

mentallurg
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