Sometimes, they say they will give you a cellphone load in exchange. https://vivako.us/%EB%A1%9C%EB%98%90%EC%B6%94%EC%B2%A8%ED%86%B5%EA%B3%84-%EC%84%B1%EA%B3%B5%EC%A0%81%EC%9D%B8-%EB%A1%9C%EB%98%90-%EB%B2%88%ED%98%B8-%EC%83%9D%EC%84%B1%EA%B8%B0%EC%9D%98-%EB%B9%84%EB%B0%80/