Debrand your M600i!

KulanKendi debranding on the M600i : Symbian phones : Sony Ericsson @ Esato

If you’re not too happy with the crappy branded firmware of your phone, then use this service to flash it with a generic firmware. Well rather to change the ID (CDA) of the phone to a generic pne, rather than a phone company provided one. Then to use the Sony Erriccson online service to update the firmware to a more recent and unbranded one.

Works fine!