THE next time you use your international calling card, think again. A survey by Sunday Money shows that you may be better off using the regular International Direct Dialling service provided by Hongkong Telecom. For those using an international calling card, however, Hongkong Telecom was a bare four per cent cheaper overall than its closest competitor, City Telecom International and about 40 per cent less expensive than MCI in a survey of calls to five select countries. We asked Hongkong Telecom, City Telecom, A T & T, MCI and Sprint to tally the total cost of a 10-minute call between 7 am and midnight from Monday to Saturday to five international destinations - the United States, the United Kingdom, Canada, France and Indonesia. For a 10-minute call to the United States, City Telecom's charges are 20 per cent cheaper than their nearest rival. City Telecom charges $98.40 while closest rival Sprint's fees are $123 for 10 minutes. Users of Hongkong Telecom cards pay $125, MCI card holders are stuck with a bill of $131.10 and A T & T calling cards pick up a tab for $136.66. The International Direct dialling charge is $123. However, for 10-minute calls to the United Kingdom consumers who use Hongkong Telecom's card pay 24 per cent less than City Telecom card-holders. Hongkong Telecom card-users pay $107, and nearest rival City Telecom's card-members $142. At the same time, MCI card-members are billed $227.72. The International Direct dialling charge is $105. A T & T and Sprint were not able to provide a service to the United Kingdom for customers calling from the territory. In a 10-minute call to Canada, City Telecom fees are again 20 per cent less than their nearest competitors Sprint and A T & T. City Telecom card-holders pay $93.60, while Sprint and A T & T customers are charged $117. Hongkong Telecom card-users are charged $119 and MCI card-users $119 while MCI card-users pay $227.72. The International Direct Dialling rate is $117. City Telecom is able to provide the cheapest peak hour rates for international calls to France as their charges are 20 per cent less than Sprint. City Telecom card-holders pay $126.40 for a 10-minute call, while nearest rival Sprint's customers are billed $158. Hongkong Telecom card-users are charged $160, MCI and A T & T card-members pay $227.72 and $251.93 respectively. The International Direct Dialling rate is $158. Sprint edged out Hongkong Telecom card rates in 10-minute calls to Indonesia. Sprint charges $105, while nearest rival Hongkong Telecom card-members pay $107. Meanwhile, city Telecom card-members are billed $185.80, MCI card-holders $227.72 and A T & T customers $241.96. The International Direct Dialling rate is $105. There are no application fees to apply for a Hongkong Telecom International or City Telecom International calling cards, but consumers wishing to become Sprint, A T & T or MCI customers must be credit card holders. Ms Ophelia Ngan, consumer marketing manager for A T & T Communications Pacific recommended that Hongkong residents use the International Direct Dialling service wherever possible. ''Calling cards are a convenience for travellers,'' said Ms Ngan. ''Not a replacement for IDD in Hongkong.''