Hi, I have a customer with an odd problem. UCX250 updated with infinity 5010's in xstim mode. Their phones were connected on the 2nd lan port on the ucx via a poe switch, but the customer decided to move them to be on the main network . There are only 16 phones, so they did not use a vlan to connect them, just their standard DHCP on the main network. Since then they have had an intermittent, yet often, problem with a ring back tone when you lift a handset on the phone. Example, : you lift the handset , and it immediately sounds like you are calling somewhere else without any info on the display. Nothing answers and it shows no active state on the operator panel. You can actually dial a phone number, and it will connect, but the ringback tone is always there and playing in the background (making the call almost impossible). If you receive a call, the problem disappears for a short time (15 minutes), then it reappears again. The problem exists on multiple phones throughout the day. The first step I took was to deregister and reregister 3 of the most used phones. The problem is gone for now, but it will take days of ‘wait and see’ to know if the issue is fixed. Does anyone have any insight on troubleshooting or knowledge of this as a known issue? Thanks in advance...