When using 3G or 4G internet on my phone, is this running over the SIM card or is this similar to WLAN traffic?

Can a mobile network provider assign my mobile internet traffic to my phone by either the SIM card number or the IMEI of my phone?

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    I think its the SIM card. IMEI is just like a MAC address in case of a computer. I don't think they can activate the 3G connection on a mobile(without a SIM card) by just using IMEI. Do you mean that if your network provider can find out what your are doing on the internet via 3G? Sorry, I didn't understand your question. – ρss Jun 3 '15 at 14:50
  • Yes exactly, i'd like to know if my mobile providor (i have a contract running on my name) can see what i am doing on the internet or if he can just see what all users connectet to one 3G or 4G tower are doing on the internet. – Junior J. Garland Jun 3 '15 at 21:02
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    @JuniorJ.Garland yes, they can see all traffic in their network, traced both by SIM and IMEI. – Natanael Jun 4 '15 at 0:45
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    @JuniorJ.Garland Yes, your ISP can see all the traffic (encrypted + unencrypted). They can't do much if the traffic is encrypted for eg. if you use https etc. However the unencrypted traffic or plain text traffic can be analysed to get your credentials and other sensitive information! – ρss Jun 5 '15 at 7:36

All the things in mobile operators are assigned per SIM card. You have stored in HLR 3 parameters: MSISDN (your phone number), IMSI (internal customer identifier) and ICCID (SIM card serial number). Based on those parameters in different subsystems of mobile operator are created CDR (call detail record) for voice and data traffic. Once per month (for postpaid) and in the moment of usage (for prepaid) those CDRs are used to generate billing information for your account

IMЕI is not used for authentication/billing. The only moment when IMЕI is in charge is when this number is in black list of stolen or lost devices and depend of policies provider can permit or deny traffic (voice and/or data) to the device

P.S. And for each call, SMS, data packet is created such CDR. Sometime is possible mobile operator to sniff for data traffic (in charging proxy for example), but this depend of operator, law, etc.

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    Brilliant details. +1 – ρss Jun 5 '15 at 7:37

SIM card is basically a smartcard with authentication data on it. The traffic doesn't go through the SIM card physically, the card is merely used for authentication and "logging in" to the provider network and is used by the operator for billing and other subscriber-specific operations. The traffic itself is then in a way similar to WLAN.

  • So i guess the provider will see the whole cloud of traffic going through one 3G providing tower but is not able to tell which contractor is doing what exactly? – Junior J. Garland Jun 3 '15 at 21:06
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    @JuniorJ.Garland, the mobile provider can definitely associate your network traffic with your account. You logged in to their network, after all. – Celada Jun 3 '15 at 22:34
  • to my understanding the provider network can see the phone's hardware address but for allowing it to connect to his network the phone must first be authenticated by the operator (which can be a different company). For the authentication purposes the SIM card is used. Both the operator and the provider then know which SIM card was used to authenticate which device, therefore they can track the traffic to a SIM card. Remember that you can use more devices per SIM card through the card's lifespan. – mikky Jun 4 '15 at 7:16

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