Is the phone getting a DHCP address?
If not then you could always add the IP info manually
Press and hold the Volume up/down keys together then release the down key (still pressing the up key all the time)
Type on the numeric (keypad) 234 then release the up key
You should now be in the phone configuration
Press * to configure network parameters
press * to view current values
press up/down volume keys to view
the phone should have an IP address,Default gateway, Subnet Mask, ICP address (maybe already present if configured via the teleworker option) & TFTP Server if the DHCP server has been contacted.
If the only field that is populated is the Current controller IP and all the others are 0.0.0.0 then the phone is not getting a IP address from the DHCP server.
You can give the phone static IP settings via
press the volume down key until you get 'view current values'
Press #
Press #
Press #
Press #
you should see Modify Static values
Press *
Now fill in the IP address, Subnet Mask, Gateway, ICP and TFTP details
scroll through until the end and save the data and reboot the phone
I would stress however that if this works then you have an issue with your DHCP server either not contactable via vlan routing or not correctly configured to provide DHCP requests to Mitel ip phones
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