A random note because this was so hard to find. If you are installing a Shoretel phone system with rebranded 3com switches such as the HP V1910, make sure that your DHCP server is set to only be on its main VLAN. I still don’t understand why, but somehow if the server is available on that VLAN, even if it doesn’t understand VLAN traffic and should ignore all except untagged, it can still mess up the process of the phones getting an IP address on the voice VLAN.
Looking for the original source again so it can be cited properly.