I worked as an operator for a major telecommunications company in the US. Although my mother tongue is Filipino, I am quite fluent in English. But there were times that Spanish-speaking costumers would call. I would usually use a spiel and transfer them to the Spanish queue. I speak and understand a little Spanish so I was confident. There was a time when a Spanish-speaking costumer went through and there was a long queue that she got irate. She didn't want to get transferred and wanted to discuss her bill with me in Spanish. I tried at first but it basically went nowhere. Luckily, she was also fluent in English. She just never told me. In that line of profession, average handling time per call is important and the moment she started speaking English was when I almost lost it. Looking back, it was quite funny experience. I never realized it until I resigned.