The full-size SIM was the first format of SIM cards, issued all the way back ... upgrade from 3G to 4G as the older SIM lacked certain capabilities. This is not the case for switching from 4G ...

A multi-carrier GSM phone with two, three or four SIM cards. Dual-SIM phones are popular with global travelers who use local and foreign carriers as well as people who want a business and personal ...

Seoul (AFP) – South Korea's largest carrier SK Telecom started on Monday to replace mobile SIM chips for its 23 million ... The company has vowed to take full responsibility and asked users ...