Subscription Management

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Why Subscription Management is required

In order to register a SIM-module in operator’s network, it’s necessary to download operator’s mobile profile onto SIM-module. Mobile profile is at least an IMSI and a set of secret keys for authentication.

Symmetric key exchange, organized within the "Request" smart-contracts from first transaction is very useful for such kinds of interactions in BT, allowing parties organize fast and secure communication channels, saving time and resources spent for extra challenge - response handshakes between operators' equipment.

It allows secure downloading of Assignee mobile profile on the end-user's SIM-module or exchanging any kind of secret data between participants. The necessary symmetric key can be obtained by both parties from "Offer" and "Request" transactions.

Downloading of mobile profile is performed in accordance with one of the standards for the telecom industry described below.

Built-in OTA platform

BTClient has built-in OTA platform developed in accordance with the "GSM 03.48 "Security Mechanism for the SIM" standard. It means that the platform provides high-secure preparation of binary SMS with credential data using unique OTA keysets assigned to each SIM-card by SIM vendor:

1. Mobile profile preparation is based on OTA Template defined in the "BTCient Web Account". The template contains following mandatory instructions called "APDU commands":

* Secure header, with SPI, TAR, PCNTR and RC/CC/DS
* Slot ID (2 .. 16) where the profile is downloaded
* Ki
* OPc
* Service Provider Name ("SPN")
* SIM Menu item 
* Mobile Country Code ("MCC") list where the profile is workable
* Call Control: short number (2 - 3 digits) to activate the profile manually via Dialer

2. Additional settings could be defined by Offer Assignee who owns the mobile profile:

* Milenage constants (default values are in the table below)
* PLMN list
* USIM Service Table
* Initial Sequence Number ("SQN") value ("0x FF 00 00 00 00 00" by default)
* Initial Location Information ("LOCI") value ("0xFF FF FF FF FF FF FF 00 00 FF 01" by default)
* Initial Packet Switched location information ("PSLOCI") value ("0xFF FF FF FF FF FF FF FF FF FF 00 00 FF 01" by default)

3. Prepared list of APDU commands is encrypted by OTA keys ("KID" and "KIc") as described in "GSM 03.48 "Security Mechanism for the SIM" standard

4. Encrypted APDU commands are combined into concatenated SMS which are sent to the end-user's Multi-Account SIM-card via Request Issuer SMPP server.

As a result, a new mobile profile is ready-to-use on the subscriber's SIM-card. It's activated automatically on arrival to a country specified in Mobile Country Code ("MCC") list. In case of any troubles with activation, end-user can select the profile manually via Dialer: it's enough to enter short number specified in "Call Control" command.

Milenage constants are following:

Constants Bytes Default Value
R1 1 byte 0x40
R2 1 byte 0x00
R3 1 byte 0x20
R4 1 byte 0x40
R5 1 byte 0x60
C1 16 bytes 0x00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
C2 16 bytes 0x00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01
C3 16 bytes 0x00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 02
C4 16 bytes 0x00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 04
C5 16 bytes 0x00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 08

Usage of own OTA platform

You can use own OTA platform to prepare and download binary SMS. Please check if the platform complies the "GSM 03.48 "Security Mechanism for the SIM" standard.

It should support following parameters:

* Ki
* OPc
* Milenage constants
* PLMN list
* USIM Service Table
* Initial Sequence Number ("SQN") value
* Initial Location Information ("LOCI") value
* Initial Packet Switched location information ("PSLOCI") value

Subscription Management Data Preparation (SM-DP) platform

"Remote SIM Provisioning (RSP)" standard was developed by Association of mobile operators called "GSMA" and described in SGP.02 specification. This standard provides global interoperability between potentially different MNO deployment scenarios, different makes of network equipment (for example SM-DP, SM-SR) and different makes of eSIM platforms. As a result, it allows easy downloading of multiple mobile profiles onto eSIMs via mobile data channel.

The main interfaces between mobile network operator (MNO) and "Subscription Management Data Preparation" (SM-DP) / "Subscription Management Secure Routing" (SM-SR) platforms are "ES2" and "ES4":

SMDP MainDiagram.png

1. The MNO owning the Profile to download shall call the “ES2.DownloadProfile” function with its relevant input data:

SMDP CreateISDP.png

2. Secure Channel between SM-DP and eSIM complies "Secure Channel Protocol 03" (SCP03) defined by GlobalPlatform:

SMDP Security.png

3. As soon as secure channel is established, the profile is started downloading:

SMDP DownloadProfile.png

4. And the last step is to enable downloaded profile via “ES4.EnableProfile” function:

SMDP EnableProfile.png