The M2M-720-A module is specially designed for the remote maintenance solution with voice streaming. This module provides 2 major technologies on networking: Voice streaming and Pair connection. The Pair connection means that the user can operate remote COM port device via Ethernet TCP/IP protocol just like a local COM port and the Voice streaming means the user can talk to remote operator while operate remote COM-linked devices. Refer to the following graph. Furthermore, M2M-720-A integrates the Virtual com technology. That can resolve the insufficiency of real com port in PC. By applying this technology, the maintenance man can take the remote maintenance or monitor whatever time or place.