CALL-BACK services can slash 50 per cent off the cost of international calls but technical problems and inconvenience can disappoint users.
Picking the right service can help avoid many problems but the variety and rapid increase in numbers make it difficult to make a choice.
Call-back services exploit differentials in the international call rates charged in different countries. A consumer dials a number in the US, for instance, where the call-back computer is located. The computer identifies the caller without answering the phone, thereby eliminating any immediate charge to the caller.
The caller is called back when the appropriate connection is made, and the outgoing call from Hong Kong becomes an incoming call from the US.
The customer later pays the call-back operator the US rate, which is almost invariably a great deal cheaper than calls made through Hongkong Telecom.
Most call-back operators are based in the US or Canada, where there is excess capacity in international telephone lines and the charges for calls are relatively cheap.