Default values and operating instructions of standard two in one SIM card holder: 1. Adopt folding double-layer type, small volume, save space. Adopt international standard card holder. Integrated c

In recent years, the rapid development of SIM card connector communication technology and network technology, especially the development of wireless communication technology, further improves the degr

GPRS introduces two new network nodes: GPRS service support node (sg-sn) and gateway support node (GGSN) into the former GSM network based on circuit switching (CSD). SGSN and MSC are at the same leve