nortel phones drop out

[Network Pro]

hi,

we have few nortel phones connected to switch switch daisy chained to pc. pc and phones are on seperate data and voice vlan. but right now we dont have any QoS at all. these phones connect a CUCM over the WAN (managed by a third party). we have had complaints lately saying that the phones are rebooting (they are not seeing the CUCM server) - they start working when they are rebooted. this happens randomly - can it be due to QoS not being configured ?

THnaks

[Network Pro]

any thoughts on this please?

[Aaron H]

Iam having the same issues with Nortel 1000 phones. Several times a day the phone will reboot after which it will stay up for 10-20 minutes and then reboot again. When the phones power cycle the switches do not log a change in the port status, nor do the switches log and issues related to power.
This is happen on two different switches, a 4507R+E and a stack of 3 3850's, in different areas of our building. I have upgraded to IOS versions on both, cat4500-entservicesk9-mz.150-2.SG11 for the 4500 and cat3k_caa-universalk9.16.12.08 for the 3850's after being advised of the CSCvg74474 software bug.
https://urldefense.com/v3/__https:/bst.cloudapps.cisco.com/bugsearch/bug/CSCvg74474__;!!IECxBNJ3jonIpDRP4g!PTOn-jY4ZzcUSYcDWKxMBbjiX7lX7M5LvZflXkCpoPkFNLicS9AF0MkNxCUy6uh2oJBemdwP5IM5BJ6Je1FukZ2n7g$

The thinking at this point is that there is a bottleneck in traffic going to the voice infrastructure. All phone traffic goes through a 1 Gig link to reach the voice servers.