OK everyone, after some more searching - obviously din't look hard enough to begin with...
- I found the solution and here it is:
"I changed the smart dialing country code to unknown and it works fine with italian and american numbers, try that option
" many thanks to ciaodom, credit to who deserves it.
The one and only drawback is that with this setting YOU DO NEED THE + SIGN IN FRONT OF THE COUNTRY CODE or else the call will still fail with the message "number unobtainable"
Hope this will be some use for someone... Cheers,