I have been with Frontier for many years --- TV., phone, Fios, the whole works.. It has been so long since I first got hooked up, I don't remember when.
I have never talked to any Frontier's representatives on the phone who are in Asia or anywhere outside of the US. Yes, some of those representatives do have an accent, but they are regional American accents, not a foreign one. Believe me, I talk with people in Asia all the time.
Sage2123 is right. All Frontier call centers are in the good old USA.