Hi Dave,
You will need to edit the jabber-config.xml as below:
<?xml version="1.0" encoding="utf-8"?>
<config version="1.0">
<Directory>
<BusinessPhone>ipPhone</BusinessPhone>
</Directory>
<Options>
<Start_Client_On_Start_OS>true</Start_Client_On_Start_OS>
</Options>
</config>
Then load the file on TFTP server and restart TFTP service.
HTH
Manish