If you are unsure what ghost calls are, you can click the link below to read about it in more detail:

In order to eliminate ghost calls from your Yealink T48G, you will need to access your Yealink's IP address. If you don't know how to find your Yealink's IP address, you can follow these links for help:

Once you have found your Yealink's IP address, enter it into a new browser window and log in. The default username and password is admin.

After you have logged in, navigate to Features and then click the General Information tab. Halfway down the page you will see a 'Accept SIP trust server only' option. Enable it and then click Confirm. Your phone will now no longer receive ghost calls!

Note: With some Yealink firmware (mostly V73 and v80), you'll need to disable IP calls. You can do this by going into the web configuration > Features > General Information tab and setting the allow IP call value to “disabled". Click the confirm button to accept the change.