FastCall works in Professional Edition as a “call logger.” We log and score your calls; and give the ability to take notes from a simple-to-use widget added as a Salesforce Home Page Component.
Using the Free Version of FastCall is a completely free option that will log calls, but not dial (or record calls, control caller ID or drop voicemails).
In order to add Twilio to dial and control calls we require Salesforce “Sites” an Enterprise Edition and above feature. We pass the call instructions to Twilio using Sites. Twilio is the telecom part of our app.
Please vote for our idea in the Salesforce IdeaExchange to allow Sites to be added to a Professional Edition Org.
You can also email your SFDC AE and ask for Sites to be added to your PE org. If you do email your AE, please CC help -at- fastcall.com. We can lobby for you.