Just installed 3cx in our small office a couple weeks ago. 14 users, using Polycom IP 650 handsets. We have an Cisco SPA8800 setup with 4 incoming Analog lines. We've had issues since it started with intermittent echo. The echo is on our end, you can hear your voice echoing back at you. The worst part is the inconsistency of it. Every test call I make sounds fine, but the users in the office are still complaining that it's happening. They say it doesn't matter if it's an Inbound or Outbound call or if they're calling a Cell # or Landline. It can happen anytime. I have the Echo Cancellation turned on, I tried turning it off which only made it happen on every call. Setting the SPA To PSTN Gain: to -3 did seem to help a little. I have the PSTN To SPA Gain: bumped up to 4 because the line is so quiet otherwise its hard to hear the other party. Any other ideas besides switching to a Patton VoIP Gateway?