Porting number whilst abroad

I'm currently with Smarty. I want to port my number to giffgaff whilst abroad.

According to Smarty, this is not possible: https://help.smarty.co.uk/en/articles/7172608-can-i-switch-when-i-m-abroad

According to giffgaff, it is: https://community.giffgaff.com/d/33942072-using-pac-code-while-oversea

It seems that Smarty is referring to a transfer-in, whereas what I want to do is a transfer-out. How can I get a definitive answer on whether this would work?