Hi Fabien,
I have mucked around with the fedexcarrier.php and the database around a little and I realised a few things:
Yes, the address in the Back Office will run a test call to the webservice with the start and ending address, and that also sets the starting address for calls made to the webservice in the Front Office when a user wants to check the shipping cost.
However, with the Miami Address as the starting address, it doesn't work with addresses outside of U.S.
Here is my test summary in the format, <starting address> --> <ending address> = <result> :
Miami Address --> Miami Address = Works.
Miami Address --> California Address = Works.
Miami Address --> UK Address = No carrier found.
Miami Address --> Singapore Address = No carrier found.
Miami Address --> Malaysia Address = No carrier found.
Singapore Address --> California Address = No carrier found.
Singapore Address --> Malaysia Address = No carrier found.
Singapore Address --> UK Address = No carrier found.
I enabled all the carrier types and the starting addresses are set in the Back Office.
Any help is appreciated. Thanks!