Hong Kong has some of the highest penetration rates in the world for both fixed-line and mobile phones; there are now more mobile phones registered than adults, and there are still almost as many domestic fixed-lines as there are households. This paper looks at the practicalities of mobile phone surveys in Hong Kong and the differences in sampling frame for mobile and fixed-lines and compares the results for the two frames for both objective and subjective questions. It also compares in detail the contact and success rates for the two frames and discusses the implications for fieldwork arrangements.