Custom phone number format with accepting 8 or 9 digits GOOGLE SHEETS

I want to format a cell to properly display phone numbers, but the number of accepted digits are 8 or 9. It is ok displaying 8 digits with this number format "387" ## ### ### and looks like "387 12 345 678", but when enterin 9 digits it look like this "387 123 456 789" but i want "387 12 345 6789"