In this paper, we use simple 3G modem cards to design and deploy a novel gateway bridging IP network and Wideband Code Division Multiple Access (WCDMA) 3G mobile network in Hong Kong. A simplified Session Initial Protocol (SIP) is devised to implement the gateway together with the 3G-324M protocol. Compared with the existent similar gateways, our gateway is much more implementable and less cost. Using the proposed gateway, we devise and develop a Video Instant Message System (VIMS) which achieves direct audio and video communications from terminals of the Internet like desktop to 3G mobile phones. Moreover, we produce and accomplish a Mobile Robotic Car Remote Control System (MRCRCS) based on the gateway and VIMS. In the MRCRCS, individuals can distantly control the moving direction of a robotic car by using a VIMS client or a 3G cell phone. By a series of practical experiments, we testify the efficiency and robustness of the gateway and its application scheme. © 2013 Springer Science+Business Media New York.