4 Ports Modem Pool is a big bulk sms machine which consists of 4 of 4G modems. The modem pool provides an efficiency way for management of numbers of modems. After connecting the modem pool to the computer through USB cable, the computer shows 4 COM Ports. You can use 'AT Command' or some software to control each of the modems for sending SMS and changing imei. Technical Parameters: (1)Type: 4 Port 4G Modem Pool. (2)Module: SIMCOM SIM7600. (3)Working Frequency: *SIM7600E: LTE-FDD B1/B3/B5/B7/B8/B20 2100/1800/850/2600/900/800MHz, UMTS/HSPA+ B1/B5/B8 2100/850/900MHz, GSM/GPRS/EDGE B3/B8 1800/900MHz. *SIM7600A: LTE-FDD B2/B4/B12 1900/1700/700MHz, UMTS/HSPA+ B2/B5 1900/850MHz. *SIM7600SA: LTE-FDD B1/B2/B3/B4/B5/B7/B8/B28 2100/1900/1800/1700/850/2600/900/700MHz, UMTS/HSPA+ B1/B2/B5/B8 2100/1900/850/900MHz, GSM/GPRS/EDGE B5/B8/B9/B2 850/900/1800/1900MHz. (4)Interface: USB Port. (5)Power Source: 5-24V DC. (6)Support Bulk SMS/IMEI Change/AT Command/Send and receive SMS. (7)Control via AT Commands. (8)Packing List: One unit Modem,One Piece USB Cable ,One Piece Power Supply Adapter,One Piece Driver CD,4 Pieces Antennas.