I've got a bunch of polycom VVX sries phones logged in to Lync 2013 using PIN authentication. Everything worked fine, then suddenly several phones spontaneously logged out automatically. Re-keying in the same pin logged the phones back in again.
Yesterday, another phone logged out, but this time keying in the same PIN didn't work. I reset the PIN using the set-CsClientPIN cmdlet, and was able to log in.
The timing of the first incident (exactly 6 months since the phones first logged in) made me think that there was some kind of PIN expiration somewhere. But checking the pin policy showed that it was set to 'Never Expire'.
I'm kinda stumped here. ANyone know if there's some kind limit to how long a device can be logged on to Lync? Or perhaps its a polycom phone setting?