6867i 6.2 Firmware Interesting Issue

[crazyscout]

So we recently started upgrading to 6.2 firmware for our 5k or so Mitel phones from 4.0. We got through about 1000 phones without any issues but a small batch of 20 phones in this latest push ended up having some issues registering. Configuration doesn't change, the phones don't fail the upgrade as they show they are on the 6.2 load but for some reason they all display 503 for registration status which indicates a server issue.

I tested from our SBCs to the phones and confirm that UDP 5060 is open as I get a 200OK response to an OPTIONS ping. Downgrading them back to 4.0 gets them to register again. I set logging appropriately in the troubleshooting section but the log files all show up as 0KB for some reason. I did also do a PCAP from the SBCs and can confirm no registration attempts or any traffic at all from the phones to our SBCs. Doing a capture from the phone side for all ports shows only my port 443 (Web GUI) traffic and nothing for SIP at all. Anyone ever run into anything like this and have any advice?

[bojo387]

Have you tried factory default and then set back all configurations?

[crazyscout]

Yep tried that as well, still no dice. Phone pulls the config from our server but just 503 on registration but not sending anything out on the network at all for SIP traffic. Was just curious if there is an issue with the 6.2 firmware that is maybe known.

[crazyscout]

Found part of the issue, the Outbound proxy server being a URL was causing the phone some issues. Based off of the PCAP I did where I saw no registration attempts this leads me to believe it is a DNS issue as it cant resolve our URL to an IP thus has nowhere to send a registration attempt to. The odd part is our provisioning server is configured as a URL as well so DNS must be working if it grabs configurations just fine.

Rolling back to pre 6.X firmware also resolves the issue and the phones register just fine. Anyone know if there were any kind of DNS changes in the 6.X firmware?