h1. CellularModem

If you are new to modems, or to the hardware and software architecture used in smartphones and tablets, it's a good idea to start from the "freedom-privacy-security-issues article":https://replicant.us/freedom-privacy-security-issues.php .

Once this is done, there are more documentation on various aspects of the Cellular modem, from the protocol to implementations details.

* [[BackupTheEFS]]: The EFS is a partition that contains modem data like the IMEI. If that partition is lost or corrupted, the modem doesn't work anymore, so be sure to backup it.
* [[CellularModemPrivacyIssues]]:
** [[ModemIsolationResearch]]: Research on how to isolate the modem
*** [[ExynosModemIsolation]]: Issue affecting devices that are not supported by Replicant anymore.
** [[LocationTracking]]: Research on how to avoid location tracking
** [[SamsungGalaxyBackdoor]]: A backdoor found in the nonfree Samsung implementation of the samsung-ipc protocol.
** [[SIMCardDetection]]: Is it possible to boot the modem with a SIM card and take it away?
** [[IMEI]]: Freedom, privacy and security issues
* [[ModemProtocols]]
** [[AT]]
** [[QMI]]: This modem protocol is used at least in the [[GalaxyS3I9305|Galaxy S 3 4G (GT-I9305)]] and the [[GalaxyNote2N7105|Galaxy Note II 4G (GT-N7105)]]. These devices need an implementation of the [[QMI]] protocol to add support for them in Replicant.
*** [[QMI-RIL]]: An attempt to implement the [[QMI]] protocol. The code can initialize the modem.
*** [[oFono-RIL]] also has an implementation of the [[QMI]] protocol that can be used on Replicant. This is now the route chosen by the Replicant project.
** [[Samsung-ipc]]: This modem protocol is used in all the smartphones (and some of the tablets) supported by Replicant.
*** [[ModemFirmwarePartitions]]: Documentations about the modem firmware partitions
*** [[XMMBoot]]: Documentation of the modem boot
*** [[XMMUpstreaming]]: Work on driver architecture toward Kernel upstreams
*** [[SamsungIpcDissector]]: Work on a Wireshark dissector and information on the packets structure
*** [[libsamsung-ipc]]: The library that implements the [[Samsung-ipc]] protocol.
*** [[libsamsung-ril]]: The library that interfaces [[libsamsung-ipc]] with Android.
*** [[ModemDisable]]: Documentation on how to disable the modem. Currently applies to devices with the [[Samsung-ipc]]. This is needed because the flight mode doesn't disable the modem at all.
**** [[ModemDisableResearch]]: More in depth documentation and research on how to disable the modem on various devices and research on user interfaces for it.
*** [[SIMnotRecognized]]: A bug in libsamsung-ipc that affected Replicant 6.0, which resulted in SIM cards not being recognized.
*** [[XMMProtocolInterfaces]]: Research on the interfaces available (for AT interfaces on with usb_sel, and diagnostics, protocol tracing etc)
** [[OtherModemProtocols]]: A list of other modem protocols and their implementations