BACK in 1987, when the birds were still singing - and Cable and Wireless was so secure in its franchise it could say such things - company barkers used to claim it was cheaper to call New York than for New York to call Hong Kong. What they did not say was that it was only cheaper if your calls were only three minutes or so. AT & T, for instance, made it expensive only for the first three minutes before dropping its rates to a level that would encourage people to keep talking. Cable and Wireless charged the same amount for the first, the 20th or the 60th minute. Its claim was only true in the narrow sense, but companies that do not compete do not even have to be clever most of the time. It was not, for instance, clever when it came to charging for data transmission in the early days. Cable and Wireless had a convoluted levy that involved an expensive mix of characters and lines. Transmitting data was as pricey as noshing on truffles. And woe be to the typist who liked many line breaks. Enough people were angry about this that I was compelled to ask the colonial types at the top what was going on with their horrific data charges. It transpired that there had been a problem with the computer billing system, or rather there had been a problem with how the machine computed what was being transmitted and how that data were translated into charges. It was not exactly their fault, someone said. They seemed to blame the computer or the company that installed it. And the ''fault'' had been allowed to pass for months. No amount of complaints moved the company to fix this huge accident of a profit centre until the story got into the newspapers. It was on one of my periodic visits to the ''colonial office'', sorry, Cable and Wireless/Hongkong Telephone, that I heard of the technological magic that was just around the corner. Soon, someone said, we would be able to use phones where you would get a read-out of a caller's number on the display. The wonder of it! Calls from the bank manager, or the previous spouse, could be artfully avoided while you were free to answer other calls. The technology was available and it performed much better than expected. Caller ID, it turned out, meant that Hong Kong callers could call North America and be identified without making a call termination, as it is known in the trade. Overseas friends, family and associates can then call Hong Kong and everyone can chat away at cheaper rates charged by AT & T or Sprint (ironically, now affiliated with Cable and Wireless). Families across the Pacific have long been splitting bills with people calling from the other side. But one Seattle-based company has taken things a step further and fashioned a business around the huge discrepancies in IDD rates in voice and data connections. KallBack thrives on companies such as Hongkong Telecom. For those who do not know this wonderful system, it goes like this: you call in, establish your ID during the first ring, then hang up and they call you back. At that point, you are effectively on a US network with all the lower long-distance and IDD rates that are applicable. KallBack users can often end up paying half what they would pay in commercial reverse-call rates offered by AT & T and MCI, let alone what they would pay our friends with their bag load of value-added services. The system also gives overseas users access to US toll-free 800 numbers - in some cases, the only numbers for software help lines. You are billed on your credit card. KallBack also has the potential of getting you around tricky political situations, such as making a ''greater China'' conference call that hooks on Hong Kong, Taipei and Shanghai. Try to arrange that with Telecom and see where it gets you. KallBack is okay.