Replicant

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.

*** [[XMMBoot]]: Documentation of the modem boot

*** [[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.

*** [[SIMnotRecognized]]: A bug in libsamsung-ipc that affected Replicant 6.0, which resulted in SIM cards not being recognized.

** [[OtherModemProtocols]]: A list of other modem protocols and their implementations