多频是指手机（无线手提电话）可同时支持使用同一种技术之不同波段。

最初欧洲GSM使用之波段为900MHz，后来个人通信服务 (PCS) 使用1800MHz，能同时使用此两个波段就称为「双频」；北美起初主要使用1900MHz，连同添加之850MHz亦称为双频。

In telecommunications, a multi-band device (including dual-band, tri-band, quad-band and penta-band devices) is a communication device (especially a mobile phone) that supports multiple radio frequency bands. All devices which have more than one channel use multiple frequencies; a band however is a group of frequencies containing many channels. Multiple bands in mobile devices support roaming between different regions where different standards are used for mobile telephone services. Where the bands are widely separated in frequency, parallel transmit and receive signal path circuits must be provided, which increases the cost, complexity and power demand of multi-band devices.