Introducing The Affiliate Brand of Reolink - Camovue, Your Next Hunting & Trail Cameras

[Reolink.Oskar]

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[Chopstix]

@reolink-oskar from the link, "The included SIM card auto-selects the strongest 4G network". So subscription is to Camovue, not the carrier of your choosing? There are some handheld radio companies moving to a direct subscription model vs carrier-based.

[joseph_1979]

@chopstix Let me give some details on SIM.

Every mobile operator orders SIM cards from SIM manufacturers. Each SIM comprises an identifier ICCID, IMSI and the authentication key Ki amongst other parameters and applets. 

The Integrated Circuit Card Identifier (ICCID), an identifier of the actual SIM card chip itself. ICCIDs are also used to identify embedded SIM (eSIM) profiles. This ID can be up to 23 digits long, including a check digit calculated using the Luhn algorithm.

The International Mobile Subscriber Identity (IMSI) identifies SIM cards uniquely by their individual operator in a cellular network. The IMSI is stored as a 64-bit field and is communicated to the connected cellular network. In the core of a mobile operator network, the IMSI is used as main identification for obtaining further customer and device specific data.

All SIM cards contain cryptographic keys. The secret authentication key called Ki is unique and is stored on the ROM, a protected area of the SIM. The Ki is never exchanged between the mobile device and the network. Its purpose is to derive sub-keys that perform the necessary authentication procedures when a mobile device tries to join a carrier’s network. The Ki is also stored on the carrier’s network within a component called the Home Location Register HLR or lately with the introduction of 4G and IMS this is being referred to Home Subscriber Subsystem (HSS). The Ki is only known by the SIM manufacturer and a few persons handling the HLR programming. The IMSI and the Ki have to be inserted in each subscription.

So when you switch on the camera or smartphone, there is the IMSI attach whereby the mobile will forward the IMSI to the Radio access network (BTS for 2G, NodeB for 3G, eNodeB for 4G) and from the RAN to the MSC (for calls) and SGSN (3G data) or MME (4G data). This IMSI attach message will end up in the HLR which shall authenticate the SIM. So if the IMSI is defined on the HSS then the IMSI attach procedure will continue otherwise it will be rejected. And an IMSI can only belong to a mobile operator. Thence to connect to another mobile operator you need another SIM card which has different IMSI identifier. The MCC is the same but the MNC and SN will be different.

I hope that Reolink should start to add eSIM where there is no longer the need of any physical SIM. This innovation offers the same functionality as a regular SIM card but with an added unique capability: it is programmable, allowing for enhanced flexibility and ease of use. This programmability empowers users to seamlessly switch network operators without needing to physically swap cards. You just buy a plan and they will ask you to scan a QR code and then enter some details the details (like apn)

Now a GSM module integrated on smartphone or any device to be connected to GSM network is continuously checking the power of adjacent cells. If the calculated power is better that the one being connected to, the module shall request a location update to the mobile RAN with the new cellid it wishes to connect to. It could be a 3G cell rather than 4G depending of the module is allowed to anchor to 3G (UTRAN) networks. It could be that the mobile is on the edge of an area and it will be continuously changing LAC/RAC/TAC.

So I guess that in their previous 4G cameras, the GSM module was not able to compare the power of adjacent cells and request a LUP.

I know this area quite well :). And now there is VOLTE which requires IMS.