Over 2,600 fake mobile base stations have been seized and 24 sites manufacturing illegal telecoms equipment shut down as part of a massive nationwide operation involving nine central government and Communist Party of China departments. China's Ministry of Public Security said that it had identified 3,540 cases of suspected crimes, including one case where a Liaoning Province gang is suspected of sending out over 200 million spam messages.
Cybercriminals normally use either a GSM modem, an internet short message gateway and an SMS server to send out spam messages. The GSM modem sends and receives text messages, with slots for several SIM cards at once. A 16-slot GSM modem can send out 9,600 spam text messages per hour.
An internet short message gateway, which connects to a PC and sends messages out over the internet, is even better for sending out spam messages as the equipment was designed to be used by mobile network operators and is many times faster. Some cyber criminals invest in an SMS server, which pretends to be a mobile base station and uses a high power signal to trick all smartphones in the same geographic location to disconnect from the real mobile base stations.
The server sends out up to 3,000 malicious spam text messages a minute and even hijack a mobile phone in five seconds.