When importing DHCP scopes and settings from a Microsoft DHCP with the Data Import Wizard, it’s important to verify that the DHCP options are correct.
This is especially important when dealing with IP telephones.
Recently, when I helped import some DHCP data from a Microsoft DHCP server, the Data Import Wizard changed the call server option (Option 128 for Nortel) from “String” to “Text”. You might guess the result.
If you more information on the correct syntax for “Call Server Information” (Option 128) for Nortel IP telephones, use the following blog post by Michael McNamara as a reference.
DHCP Options (VoIP)