It is a device capturing and controling all the signals, which are being created by the whole system, especially the made and received phone call signals. The device is mostly used for connecting regular phone system with the Internet and backwards.
Yeastar MyPBX Enterprise M2 is a hybrid IP-PBX, which is designed for mid-sized companies and divisions of large organizations. Besides working with VoIP-SIP and IAX, the device works effectively with connection to analog phone lines like traditional telephony.