Filling Spanish locator forms

[Grozz]

When filling spanish locator form im asked for phone number but in the dropdown list for prefix number, all i can find is GG+44 is this correct

Yes plus 44 is UK code

i know +44 is correct but what about GG that comes before it

Can anyone tell me what’s the prefix for my phone on the Spanish locator form
The drop down list has letters as well as numbers
I know it’s 44 but what are the letters

It’s GB +44.

Thank you