My solution (my college helped me a lot) Manual method: 1. dial #11 to activate SIM1 (you got general error, no problem) (or dial #22 for SIM2) 2. root shell and kill csd (xterminal and sudo -s probably) killall csd After that N900 will ask your pin code (if is set) and register the new card. It takes some seconds. Automatic mode: 1. edit a script: /usr/bin/changesim : #!/bin/sh /usr/bin/dbus-send --system --dest=com.nokia.csd.Call --type=method_call --print /com/nokia/csd/call com.nokia.csd.Call.CreateWith string:"$1" uint32:0 sleep 1 /usr/bin/killall csd #end script 2. run right for this script: chmod 755 /usr/bin/changesim Cheers, fido