AT&T Co and Control Data Corp have agreed to expand their joint Redi-Access dial-up access to AT&T’s Accunet Packet Service digital network that connects to packet switching networks in 19 countries, to 300 US cities by early 1988. The agreement means that customers soon will be able to reach public information services and databases or private host computer applications more economically. The number of Redi-Access locations may be expanded further, to 400 cities, depending on market demand. Typically, customers use a modem, and a terminal such as a personal computer to dial into Redi-Access through a local or AT&T 800 service telephone number. Redi-Access offers a pay-as-you-go alternative to private-line access and expensive protocol-conversion devices required for private X25 networks. The offering makes packet technology affordable for users of all types through the shared use of such devices. This new agreement puts the presence of the AT&T-Control Data entry on a par with established players in the public data network arena, reckons Gerald Johnson, AT&T mark-eting vice president. The agreement also calls for all Redi-Access locations to support additional optional capabilities that offer customers more flexibility than the current offering. In addition, all locations will allow customers to exchange information at speeds up to 2,400 bits per second through modems such as the AT&T Dataphone II 2224G for electronic information filing retrieval, mail and order exchange.