The present document specifies the Human Factors (HF) requirements related to all aspects of a European Telephony Numbering Space (ETNS). It describes the requirements to be met jointly by the ETNS service provider and the network operator enabling access to the ETNS service. The present document applies to any ETNS service provided within an ETNS scheme based upon a European Country Code (CC) and provided for access from public and private telecommunications networks. It covers those aspects of ETNS services that would be of importance to the users of those services and to other telephony users who may be affected by the introduction of an ETNS. Requirements cover: - the formatting of the written presentation of ETNS numbers to enable users: - to identify an ETNS service; - to minimize dialling errors caused by difficulties in memorizing long digit strings; - rules for migrating from an ETNS Service to a Global Service that will minimize difficulties for users; - rules that ensure that called users receive appropriate Calling Line Identity (CLI) information when called from a European Number (EN); - rules that ensure calling users are still able to determine call charges after a EN has been ported to a new provider; - rules that ensure the minimization of user difficulties caused by call delays; - rules to overcome the potential linguistic difficulties associated with ETNS services. Mobility aspects of an ETNS are outside the scope of the present document. Only those aspects of an ETNS to which specific requirements can be attached are covered in the present document. Other Human Factors aspects of an ETNS are presented in TR 101 056 [1].