have got 5 ata-190, and all of them have one problem - it drops registration and became unregistered after some period of time. after reboot it works fine several days and then drops it again.
tried different firmware (now it is ATA190.1-1-2-005), but it doesn't help
ATA-187 works fine.
We have the same problem with our two ATA191's. We go about 1 month and then the ATA stops working. The connection to the switch remains active, but the registration drops, we can't ping them, and no IPv4 Address is listed in CM. They have to be power cycled in order for them to work again. Using Call Manager 188.8.131.5200-11
Our older 187 ATA's never had this problem.
I think we finally found a fix! We have been stable now for over a month.
We were given the following action plan from TAC:
Please go to phone >> device >> ata devicw >> search for this parameter and disable line 2 ; click on save and then apply config
Try that out and see if it works for you.