[XPERIA X10 Q&A, Help & Troubleshooting] DooMLoRD:
The Right firmware/baseband

The latest firmwares contain OS updates, feature updates, rectified bug, etc, and are released by SE occasionally. As and when a new firmware is certified it appears on http://bit.ly/x10seupdates (this is a shortened address it will redirect u to PTCRB site) along with the date of certification. Keep in mind that although many firmwares get certified only a select few are released to the users.

Whenever a firmware is released for consumers via SE update service (SEUS) /PC companion, ALL the users DO NOT GET IT IMMEDIATLEY. These updates are always sent regionwise. Generally region specifc firmwares have different apps which are included and may or may not have some functionality. Your best bet is to go for a generic baseband for your specific model.

To install these updates unofficially, one has to flash the firmware/baseband onto their devices using tools.

*** BASEBAND/FIRMWARE FLASHING DEPENDS ON THE MODEL NUMBER OF UR X10***

*** ONLY FLASH UR DEVICE IF THE FIRMWARE IS FOR THAT SPECIFIC MODEL NUMBER (UNLESS OTHERWISE SPECIFIED) ***

MUST HAVE TOOL for base band flashing by Androxyde: http://xdaforums.com/showthread.php?t=920746

DIFFERENT flash tool X10FlashTool by Bin4ry: http://xdaforums.com/showthread.php?t=825201

*** IF U INTEND TO USE CUSTOM ROMS THEN HAVING THE CORRECT BASEBAND FOR THAT SPECIFIC ROM IS OF UTTERMOST IMPORTANCE OTHERWISE U WILL (AT WORSE) BRICK UR PHONE!!! OR BE STUCK AT THE BOOTING PROCESS OR WILL HAVE VARIOUS CRASHES (aka Force Close messages FC) ***

*** NOT ALL CUSTOM ROMS SUPPORT THE LATEST BASEBAND ***

* personally would recommend not to be too much in a hurry to flash when a new baseband comes out. especially if u want to use custom roms. the devs in most cases require time to port their code over so that the rom is compatible with that specific firmware. *

*** There are ways to upgrade/downgrade only the baseband. ***

Great Tutorial by steve.adams.x10 to flash ONLY the baseband: http://xdaforums.com/showthread.php?t=939812

list of SE official (released) firmware/basebands

|- FIRMWARE -|- BASEBAND -|
---------------------------
2.1.B.0.1 - 2.1.67
2.1.A.0.492 - 2.1.65
2.1.1.A.0.28 - 2.1.61
2.1.1.A.0.16 - 2.1.58
2.1.1.A.0.6 - 2.1.55
2.1.A.0.435 - 2.1.54
2.0.2.A.0.24 - 2.0.49 / 2.0.52
2.0.A.0.504 - 2.0.46

thank u stan.s for the info on 2.0.46

*** worth reading if u want to flash ONLY BaseBand

BaseBand Collection by rendeiro2005: http://xdaforums.com/showthread.php?t=960527

[FLASHTOOL GUIDE] HOW TO for n00bies http://xdaforums.com/showthread.php?t=928343

[UPDATED] X10i 2.1.A.0.435 & 2.1.1.A.0.6 for FlashTool (Rogers, Global, Nordic & Saudi Regions) by arkedk: http://xdaforums.com/showthread.php?t=936733

Head over to http://xdaforums.com/showthread.php?t=920746 for the following firmwares: [2.1 ÉCLAIR ROM] X10i/X10a generic 2.0.A.0.504 / 2.0.2.A.0.24 / 2.1.A.0.435

TO GET PHONE BACK TO STOCK, FLASH WITH GENERIC (GLOBAL) FW FROM: HERE

Slightly older firmwares/basebands:

[2.1] Dual touch by Bin4ry: http://xdaforums.com/showthread.php?t=920669

[2.1] initial release: http://xdaforums.com/showthread.php?t=825675

[2.1] Prerooted Generic 2.0.2.A.0.24 firmware (21/12/2010) by zdzihu: http://xdaforums.com/showthread.php?t=885956

[1.6] AT&T X10a R2CA016 by kbadone: http://xdaforums.com/showthread.php?t=755774