漫游（英语：roaming）指的是用户于原先申请的电信公司所提供服务的网络以外，在其他电信业者甚至是国外的电信业者所提供的电信网络范围使用语音通话、数据传输等电信服务，以使通信可以保持而不中断。

由于漫游涉及到用户认证及拆帐等问题，电信业者间需签定漫游协议才会允许双方或多方的用户可互相漫游。通常情况下，处于漫游状态的用户并不需要更换手机号码，但是在使用某些服务时可能会受到限制，费率也会有明显的提高，因此时常有用户因为在漫游时没有关闭非必需的服务（如数据网络等）而产生高额漫游费用的情况。

Roaming ensures that a traveling wireless device (typically a cell phone) is kept connected to a network without breaking the connection. In wireless telecommunications, Traditional Roaming is a general term referring to the ability for a cellular customer to automatically make and receive voice calls, send and receive data, or access other services, including home data services, when travelling outside the geographical coverage area of the home network, by means of using a visited network. For example; should a subscriber travel beyond their cell phone company's transmitter range, their cell phone would automatically hop onto another phone company's service, if available.