Open Windows Control Panel. There, click the Phone and Modem Options icon.
In the configuration window, click Advanced.
Click Add, then select SIP TAPI Service Provider from the list. Click Add in the "Add Provider" window.
Do not close the "Phone and Modem Options" window yet.
You should get a confirmation message that the SIP TAPI Service Provider was Installed...
In the "Phone and Modem Options" window, select SIP TAPI Service Provider and click Configure.
You will be presented with a pop-up window telling you the details you will need to configure SIP TAPI. Now, configure your username, password, SIP domain and outbound proxy with the details you obtained from your phone administrator.
Now that SIP Tapi is installed and configured you need to Setup Advantage Xi to dial using TAPI
Utilities > Options > Address Book > Dial Options
Select TAPI From the Dial Type Options then click OK