How SIM Connect to the Network

 

A mobile phone need tobe authenticated first to the network so it can use the services from Mobile Network Operator (MNO) like voice, SMS, and data. When the mobile phone first switched on with SIM card inside, then the authentication process in GSM network starts when the base station (BS) sending out random challenge (RAND) to the mobile phone.



Authentication and service request from the MNO following the process below :

·         When a mobile phone first switched on it will send a unique subscriber authentication key (IMSI) to the network. IMSI is programmed on every SIM card.

·         The authentication center (AuC) has a list which maps Ki number with the IMSI. It is a secure database.

·         When a SIM card requests for a service, a 128 bit random number (RAND) is instantaneously generated by the AuC and transmitted to the SIM card.

·         The A3 algorithm which is programmed inside the SIM card processes the RAND number and Ki number and generates a 32 bit output called the Signed RESponse number (SRES).

·         The same process is done on the AuC side.

·         The SIM card transmits this SRES number to the AuC.

·         The AuC compares the received SRES with the SRES that’s generated on the network side.

·         The SIM is authenticated if and only if the two SRES are same.







Comments

  1. ThailandeSIM - Best eSIM Thailand For Tourist and TravelMay 25, 2023 at 2:02 AM

    Best esim for Thailand

    ReplyDelete
  2. janeJune 4, 2024 at 9:25 AM

    Great Post! You are sharing a wonderful post. Thanks and keep sharing. IoT SIM cards are specialized subscriber identity module (SIM) cards created for Internet of Things (IoT) devices, allowing them to connect to cellular networks for data transmission. These SIM cards are optimized for IoT applications, offering features like low power consumption, global network coverage, and secure connectivity. By facilitating seamless communication between IoT devices, IoT SIM cards play a key role in enabling remote monitoring, data exchange, and efficient connectivity for IoT implementations in diverse industries. For a comprehensive overview of iot sim cards, including latest trends, expert opinions, and actionable tips, please visit this page and stay ahead of the curve.

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