SMS Problem

A little background I guess. I made my league account back in season 2, when I still lived in Puerto Rico. Before I moved to the US I had a Puerto Rico number and I haven't bothered to change it since Puerto Rico is a US territory and doesn't cause problems when calling from within the US. Now that I'm trying to sign up for clash with my friends here in the US I try US as the origin of the number and it doesn't work, I try Puerto Rico as the origin and it also doesn't work. I believe it might have something to do with the region my account is based or with the first 3 digits of my number ( it starts with 939 and when I select PR as starting region it still only uses 787 as the area number). Anyone else here have this problem? Can someone help?