British Telecom’s electronic Yellow Pages service came into service in London, Reading, Guildford, Watford and St Albans last week; the system, developed by Intercom Data Systems Ltd of Woking, Surrey, provides information under the same classified headings as in the printed books and there is no extra charge for the service above the network connection charge: the new service can be accessed from any Ascii terminal, equipped with a modem and the appropriate communications software, as well as Prestel sets, which access the database via a gateway; when the system was announced in May 1986, Telecom said that advertisers who already use the printed directory will also get publicity on-line at no extra cost.