Hi, the method you are trying is applicable for hard-phones only. The Cisco IP Phones search the DHCP IP on the voice-vlan configured on it's switchport, CIPC doesn't, so behaviour of Cisco IP Phone and CIPC is not the same at network perspective. Cisco IP Phone marks and classifies the RTP and Call Control Signaling traffic to get high priority whereas the data traffic from attached PC to less priority, CIPC traffic is also left to less priority as it's considered as data traffic. The point I'm trying to explain is, you can't expect the same behaviour from CIPC as always you get from Cisco IP Phones.
If you wish to put the default TFTP Server you have to work with Windows Registry Settings. Navigate to 'HKEY_LOCAL_MACHINE\SOFTWARE\Cisco Systems, Inc.\Communicator' and set the TFTPServer1 and TFTPServer2 in hexa format , example: 3284ea0a for 10.234.132.50.
HTH.
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