DHCP fails on Cisco handsets all other devices fine

[Paul Cobley]

So, we have a 4507 switch which is the dhcp server for our network. We have a mixture of Cisco & 3rd party handsets on our SIP phone system. This is a flat network in one VLAN. Our 3rd party handsets & all PC's can get DHCP with no problem at all. All Cisco handsets however fail to get an IP, they just sit on network initializing. We have done factory resets (this is on SPA & 7960 handsets). The switch shows :-

4d02h: DHCPD: DHCPDISCOVER received from client 0100.0b82.2d68.88 on interface Vlan104.

The config on the switchport is standrad :-

interface FastEthernet5/9

switchport access vlan 104

switchport mode access

switchport voice vlan 104

spanning-tree portfast

end

Any ideas what the issue copuld be on just the Cisco handsets ?

TIA

Paul.

[Joseph Martini]

What are the other DHCP messages you see from a debug or packet capture?  Looks like the Discover from the phone is seen by the switch, the switch should send out an Offer, followed by the phone sending a Request, then the DHCP server sending an ACK.

[Paul Cobley]

Answer was to "clear ip dhcp conflicts" database