16 Ports Modem Pool is a big bulk sms machine which consists of 16 of GSM 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 16 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: 16 Port GSM Modem Pool. (2)Module: Quectel M26. (3)Working Frequency: GSM 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,16 Pieces Antennas.