本文件的范围是调查与使用 欧洲电话号码空间（ETNS）。本研究的重点是服务之间的号码可移植性 提供商（SP），即客户可以从一个ETNS服务提供商（SP）转移到另一个ETNS服务提供商（SP），并保留欧洲客户 那个服务的号码。本文件描述了在网络环境下的号码可移植性的主要技术要求和特点 ETNS服务，并讨论了目前和不久的将来实现数字可移植性的技术 这是一种有效的方法，同时尽可能减少对网络的影响。

The scope of the present document is to investigate aspects related to number portability for ETNS services using a European Telephony Number Space (ETNS). In this study the focus is on the number portability between Service Providers (SP) i.e. a customer can move from one ETNS Service Provider (SP) to another and retain a European Number for that service.The present document describes the main technical requirements and features of number portability in the context of an ETNS service and discusses the technologies available today and in the near future for realizing number portability in an efficient way whilst trying as much as possible to minimize the impacts on the network.