in the U.S. as well as a broad range of GSM carriers worldwide such as Vodafone, Orange and T-Mobile (Excluding-US), many of whom offer official unlocking. See also 3GPP Cellular frequencies Global Positioning System Roaming UMTS frequency bands LTE frequency bands 5G NR frequency bands CDMA frequency bands 2008 United States wireless spectrum auction References External links LDpost.com – History of GSM and More GSM history, technology, bands, multi-band phones 3GPP Specification detail TS 05.05 Specification 3GPP TS 05.05 Radio Transmission and Reception 3GPP Specification detail TS 45.005 Specification 3GPP TS 45.005 Radio Transmission and Reception 3GPP Specifications for group: R4 – Frequencies info for UMTS (TS 25.101/102/104/105) Bandplans Mobile telecommunications GSM standard