Here is a summary of the article in one paragraph: Saul Goodman, Esq., a marketing expert, wants to optimize his advertising budget by tracking calls from his ads. To achieve this, he uses Twilio and Google Analytics to build a call tracking system. The system works by associating unique phone numbers with each ad type, logging incoming calls, and forwarding them to a script that extracts the caller's information and sends it to Google Analytics using the Measurement Protocol API. The script also returns three lines of XML to Twilio to forward the incoming call to Saul's main landline. By following this tutorial, readers can set up a basic call tracking system in under 10 minutes, allowing them to make data-driven decisions about their marketing budget and track the effectiveness of different ad types.