A.1 TroubleshootingA.1.1 OperationProblem Probable Cause SolutionCannot set the IP address, sub-net mask address, and PBX IPaddress to the IP-PT.An unusable value is being set. • Set an IP address within the valid range.IP address of the IP-PT/PBX: "1.0.0.0"to "223.255.255.255"Subnet mask address: "0–255.0–255.0–255.0–255" (except 0.0.0.0 and255.255.255.255)Cannot register the IP-PT. The necessary network param-eters are not set for the IP-PT.• When not using a DHCP server, set theIP address, subnet mask address, andenter the PBX IP address. If necessary,also enter the IP address of the defaultgateway.• When using a DHCP server, enter thePBX IP address.The IP-PT cannot connect to thePBX.The wrong IP address, subnetmask address, PBX IP address,or default gateway address wasentered.• Check each parameter and enter thecorrect value.The Ethernet cable is not con-nected correctly.• Check the Ethernet cable connections.The DHCP server is not active. • Restart the DHCP server.• Disable DHCP and re-enter settings asappropriate (refer to "4.2.2 Setting theVLAN Parameters").62 Information about IP Proprietary TelephonesA.1.1 Operation