A method of accessing a target entity over a communication network employs a distributed database system similar top the DNS of the Internet; indeed the DNS may be used as the required distributed database. The distributed database stores records, each associated with a corresponding domain name and holding communication data for use in accessing a target entity. Each of these domain names are related to a respective number string from which it can be derived by a process including parsing at least a substantial portion of the number string into at least a part of said domain name. Upon the input of a number indicative of a target entity, the related domain name is formed by parsing the number and the domain name is then used to retrieve the corresponding communication data from the DNS-type distributed database system. This data is then used in accessing the target entity. In one embodiment the communication network is a telephone network and the target entity is a called party; in this case, the number string comprises a dialed number and the retrieved communication data is a URI indicative of the location on the Internet of a current telephone number for the target party, the URI once retrieve being used to access the current telephone number over the Internet for use in setting up a call to the target party.