DHCP Issue with 3com switch and Inter-Tel 8662 Handsets

Hi All,

I have a crazy issue relating to nter-tel (mitel) 8662 VOIP handsets.
basically I have a 3com 4210g 24port POE switch (latest firmware)
a SBS2003 server directly plugged into it running DHCP
all the clients ranging from XP to W7 can all connect to server and pickup a DHCP address fine.
any DHCP capable device plugged into the switch pickup a IP fine, this includes printers and such like.
A test handset from Polycom and a cheap Grandstream VOIP phone both pickup DHCP ip address fine.

when I plug a Inter-tel 8622 handset into the switch it gets stuck at trying dhcp over and over.
If I manually set the handset IP I cannot ping it from anywhere on the network
If i plug a PC into the PC port on phone I cannot ping anything.

If i remove the 3com switch and replace it with a cheap netgear switch and use a POE injector to power the phone, it gets a IP perfectly.
If I power the 3com switch off and on again with the phone plugged in it will get a IP!

so basically DHCP works perfectly for every device under  the sun bar intertel IP phones.

Its a very basic setup to the level that even I rip the switch out and plug in lonesome into a DHCP capable router it all works happy and I can pickup a DHCP address on every port, apart from the intertel phoens which get stuck.
I dont need any fancy setup on the switch as it trully is a basic site with a small number of users and a SBS server.

any suggestions or advice would save me pulling my hair out any further!

Thanks
Neil
itcsupportAsked:
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from_expConnect With a Mentor Commented:
i think, that problem may be with voice vlan. are you sure, that your ip phone is not trying to use any vlan tagging?
because if it does, than this can easily explain why you can't reach network from ip phone even with statically configured address
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itcsupportAuthor Commented:
Nope by default they don't look for one and the weird thing is if we power off the switch and back on again the phone picks up a DHCP address. If we manually power phone of and on or unplug and plug it back in again it fails again. Of course its not ideal to unplug the switch every time the customer connects a phone. I will play around with the vlan settings and see if anything comes back. If it does will credit the points.
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from_expConnect With a Mentor Commented:
one more thing to look at - dynamic arp inspection if you have any on the switch.
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from_expConnect With a Mentor Commented:
and if switch reboot helps, the it must be something, which allows switch to thing of a phone like voice vlan equipment.
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itcsupportAuthor Commented:
Managed to get somewhere..

I deleted the default interface vlan 1 of the 3com switch and the phone came alive.
no what combination of  tagging / untagging on the ports or manual configuration of VLAN id's on phones seemed to work.

As this switch is purely to run the IP phones and a few PC's / Printers in a small office I can live without the default VLAN interface but will play further.

I will credit the points to you from_exp.

Thanks
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