New STSe installed in July. Both calling ends are complaining they care barley hear each other. What is something I could check for? I have connected my butt set to the CO lines and there are no issues, however when you pick up a system phone and call it is very faint. Is there a way to increase the volume for the CO lines? Handset volumes are all the way up.

You can increase co transmit volume but it isn't going to fix the incoming audio. If all ports are low you could have a bad control unit. There is one other thing, if the lines have low loop current, your test set may sound okay but it will cause the volume to be low in the system. Lines need between 17 and 22 milliamps to work and sound properly.

I'd say Derrick is right. Seems like you've got high loop current (greater than 35mA) that damaged the CO line port on the STSe. You'll have to get the unit replaced and possibly install Loop Current Regulators by Sandman on the 66 block to control the loop current to the 22-27mA range. I've had this issue several times in the recent past.

so you are saying the KSU needs to be sent in for repair? and then add the regulators to the repaired ksu?

You need to check loop current before you send in the system. It might not need to be repaired.