In Guilin and Yangshuo, there is not a taxi hotline answered by English speaking operator.  Demand on taxi is high during rainy days, peak hours (6.00am to 9.30am and 6.00pm to midnight), weekend and public holidays, but it is not easy to find a taxi station on street.  The stress of waiting for a coming taxi with many people skipping the line is unacceptable.  For people who prefer to reserve everything in order ahead of time, this pre-booking service in Guilin is what you are looking for.