SergeyTitov
07-30-2006, 13:54
It is possible to use a non-cloned SIM card for several mobile phones. Many clients will be able to use only one shared SIM for outgoing calls. For this you should use the SIM Card Sharing technology. Let us assume that you have an unlimited SIM card. The SIM cannot be cloned because it has Comp2 or 3 data encryption algorithm.
Become necessary:
1. For a server: a PC, access to the Internet, simple SIM-Reader, unlimited SIM card.
2. For a client: a mobile phone, prepaid SIM card for incoming calls with GPRS, also a special program for mobile like “MultiSIM without smart card”.
At begin of a call, the phone sends its IMSI to a GSM Base Station (BS). In our case, the phone must send the shared IMSI instead its own IMSI from SIM inserted. BS receives the IMSI and sends a random number “RAND” to the phone. The phones receives it. In classical case, RAND is being passed to a SIM. The SIM uses the RAND and an “inviolable” KI, then calculates and returns a SRES number to the phone. This result, SRES is being passed to the BS. Bs compares the SRES received and its SRES calculated at BS side. Authentication is successful, the phone has obtained a right for a call and has received a TIMSI.
In our case the situation will be some different. When the phone received RAND, it send this number to the server instead SIM card. The GPRS channel of the prepaid SIM will be used as transport. Besides, it is necessary to send to the server a login&password for access right and statistic logging. A program working on the server accepts RAND and pass it to the shared SIM through SIM-Reader. The SIM calculates SRES using the RAND and its KI. The SRES is being sent back to the client phone. The phone passes the SRES to the BS, then obtains the call right.
Masters patchwriters, you already have created more complex thing, “SIM-Emulator without smart card”. Who is able to write the program for phone-client? From my side, the server program is being developed, an enough experience in Win32 programming is present.
The predictable time for reply RAND->SRES will be about 1-3 sec. Faster is impossible imho, because “pings” in (E)GPRS are slow.
Become necessary:
1. For a server: a PC, access to the Internet, simple SIM-Reader, unlimited SIM card.
2. For a client: a mobile phone, prepaid SIM card for incoming calls with GPRS, also a special program for mobile like “MultiSIM without smart card”.
At begin of a call, the phone sends its IMSI to a GSM Base Station (BS). In our case, the phone must send the shared IMSI instead its own IMSI from SIM inserted. BS receives the IMSI and sends a random number “RAND” to the phone. The phones receives it. In classical case, RAND is being passed to a SIM. The SIM uses the RAND and an “inviolable” KI, then calculates and returns a SRES number to the phone. This result, SRES is being passed to the BS. Bs compares the SRES received and its SRES calculated at BS side. Authentication is successful, the phone has obtained a right for a call and has received a TIMSI.
In our case the situation will be some different. When the phone received RAND, it send this number to the server instead SIM card. The GPRS channel of the prepaid SIM will be used as transport. Besides, it is necessary to send to the server a login&password for access right and statistic logging. A program working on the server accepts RAND and pass it to the shared SIM through SIM-Reader. The SIM calculates SRES using the RAND and its KI. The SRES is being sent back to the client phone. The phone passes the SRES to the BS, then obtains the call right.
Masters patchwriters, you already have created more complex thing, “SIM-Emulator without smart card”. Who is able to write the program for phone-client? From my side, the server program is being developed, an enough experience in Win32 programming is present.
The predictable time for reply RAND->SRES will be about 1-3 sec. Faster is impossible imho, because “pings” in (E)GPRS are slow.