8028s - No ringtone after a while

[HelloALU]

Hello,

We are replacing 4028 phones with 8028s.

We face an issue on some phones (fresh out of the box). The phone works just fine, but after a while, phone stops ringing when an incoming call arrives. this was never the case with the old 4018/4028 phones.

We can see the caller ID on the screen, the screen lights up, the blue LED blinks, but the phone doesn't ring.

When we unplug and restart the phone, it rings fine, but stops after a few received calls.

Do you have ever faced this issue? What can be done?

Thank you.

[sadim]

Hi,
What is the OXE version