Generally SIM adapters use a fake code 001 instead of your country code
So you need to edit a file (for Expert only):
You must add an entry to simulate that SIM is of your country:
with instead of xx the identifier of your country (see previous list)
Argentina = ar , Ecuador = ec ....
Otherwise there is an application in CYDIA , in TWEAKS section ,
named "Net.-Local Number Format" , who tell
to the phone to use the international prefix of the
ACTUAL Country/Network instead of SIM or regional settings.