What language may you use for identification when operating in a phone sub-band?

Regardless of what language you use to converse with another station, the FCC strictly requires that your official station identification (your call sign) be made in English. This ensures that the US regulatory authority and other domestic operators can readily identify who is transmitting. You are perfectly free to chat in French, Spanish, or any other language during the actual conversation, but when it comes time to give your 10-minute or end-of-contact ID, it must be spoken in English. Options mentioning ITU or UN recognized languages are distractors.