With old version you can get message phone detected but it can not enter boot after it.
In new software version some things are changed.
When software can not enter boot you will not get phone detection message.
However if your phone can not enter boot you must use 2.4V adapter and RxTx pins need to be higher then others. In that case works 100%.
http://www.gsmmasters.com/Elle/C551-...al_Working.pdf http://www.gsmmasters.com/Elle/C55x-...ins_higher.pdf