Is this normal? I recently bought a "Elastix ELX-025 Sangoma 4 FXO, 1 FXS EC" from Elastix Depot, set up the SIP extensions, trunking..etc. Now I'm attempting to setup the POTS interface for backup purposes. Whenever I plug the FXS line into our POTS line, the POTS line emits a loud buzzing on a telephone on that line. (The telephone on this line is temporary) Is it normal for the FXS port to emit a loud buzzing? Obviously I've disconnected that line from the PBX for the time being, but would love to know if it's normal. Thanks!