Determine European customer by VAT reg. number [EU STCEG]

Hi!

I work in international company. For one of the countries VAT procedures, in order to know which VAT code to use, I need to know if it is a european customer.

I need to determine to which country the VAT reg. number belongs. For example, I take French VAT reg. number FR12345678, cut 2 first characters, and this way I know that it belongs to FR=FRANCE.

For each country code (FR for example) I can know if it is an european by field T005-XEGLD = X.

But, I can't find the way to determine always the country - because for Greece, for example, it doesn't work this way : Greece country code is GR and it's VAT reg. number is EL12345678

Is there a functiom module or logic to determine one of the following:

1) takes VAT reg. number and determines it's country

2) takes VAT reg. number and determines if it European

Please help,

Jana