In telecommunications, the terms multi-band, dual-band, tri-band, quad-band and penta-band refer to a device (in particular a cellular telephone) supporting multiple frequencies used for communication. Inside the cellular case, the purpose of doing so is to support roaming among distinctive countries/regions whose infrastructure cannot support cellular services inside the exact same frequency collection. Increasingly, a quad band telephone needs to be your first choice of telephone. A mobile phone that supports 4 distinct radio frequency bands. Unique cellular telephone networks about the world use various bands. A telephone can only be used on a network if it supports the correct band(s). Quad-band commonly refers to a mobile phone working with GSM technology. A quad-band GSM mobile phone is one that is usually used for basic service almost anywhere within the world. That is because most countries have at least one GSM network, and most GSM networks worldwide use one of 4 bands. By supporting all 4 bands, a quad-band mobile phone is compatible with most GSM networks worldwide.