She got angry (up until this she wasn't exactly pleasant, but she was polite) and yelled at me, “I speak English. I don't know what language you speak, but I speak English!” And then she hung up on me.
"Yes, but not well enough that native speakers can understand you."
OK, maybe not, but that is what I'd be thinking. Not their fault, I am sure (I can't even imagine trying to converse in a second language) but I've also been yelled at for not understanding some thick foreign accent. I have sometimes asked people to spell the word they are trying to say. It works, except sometimes they can't pronounce the letter either. "B-A-N..." I write/repeat, "B-A-N...." and they say, "No, B!! Not B, B!!! B-A-N...." Turns out they are trying to say P. (I'm not picking on the ethnic group that can't say "P" because I am sure there are plenty of sounds I can't pronounce in other languages, but it does make communication difficult!!)