When we use voip to replace old phone system, the stable of telephone system is the first important things. However, it is unimaginable to make voip more stable than PSTN. So what we only could to do is that when voip became bad we could change to pstn as soon as we can.
How MG3000-R backup voip with the PSTN line
MG3000-R 4s4o owned 4 fxo and 4 fxs ports. When you work in backup mode, 4 fxs ports connect to pbx trunk line, 4 fxo ports connect to CO line. User start a voip call from fxs port, When a voip call failed, MG3000-R will automatically dial on the pstn line through fxo port. The end user use the gateway like it was on voip line. So the voip call quanlity is protected with pstn backup line.
Phone System 