There are 2 options for tracking Facebook traffic.
1. Using Web Referral Trigger
For Facebook referral traffic, you can use one of “facebook.com, m.facebook.com, or l.facebook.com” as the source simply because the company sends traffic from a few different domains.
Once you pick the source, make sure you update the value within the WhatConverts dashboard.
2. Using Social/Medium Trigger in the URL
How to set up URL tagging options within Facebook to ensure it tags the visitor from the ads:
If you are using paid advertising on Facebook, we suggest using UTM parameters appended to the URLs. The UTM builder can be found here: https://www.facebook.com/business/google-analytics/build-your-url
Next, simply change your source and medium to trigger numbers based on the parameters you set in Facebook.
Lastly, update your phone number to trigger for source: facebook and medium: cpc once you have made the changes in your ads.