Digital marketing has provided businesses with an entirely new way to connect with their customers and generate new opportunities. Its growth has been explosive and it shows no signs of stopping. In fact, in a time where many marketing departments have had their overall budgets slashed, digital marketing spend is forecasted to increase to 35% of total budgets by 2016.

While we’ve seen many companies masterfully execute digital marketing strategies that generate results, there’s one aspect of digital marketing that’s consistently frustrated marketers.

That’s call measurement.

According to a new study by WPP Millward Brown Digital, more than 70% of marketing executives polled said they would increase their spending on mobile, digital and social platforms if there were better ways to measure return on investment.

Here’s a breakdown of how marketers would spend their money if they were able to track ROI better:

Source: 2015 Millward Brown Digital “Getting Digital Right” Study

Here are some of the most important call tracking metrics you should focus on as you execute digital marketing campaigns.

There are two effective ways to gather this information: Google Analytics and Call Tracking.

Google Analytics is a free web service that tracks your website traffic and compiles it into easily digestible reports. It gives users a better idea of who their audience is by gathering demographic information, site visitors’ geographic location, how they accessed your site (desktop versus mobile device versus table), what browser or network they are using and how they got to your site. By looking at the source of your traffic, Google Analytics will show you which of your digital marketing initiatives are driving website traffic.

Call tracking puts a unique phone number on all of your digital initiatives and allows you to measure media and ad campaign performance. It works using a concept call Dynamic Number Insertion (DNI). Your customers see one number or keyword, but you keep track of how they found you. We go into a little more detail in this article. If you’re looking to measure which of your digital marketing initiatives generates the most phone calls, consider call tracking. Call tracking will give you analytics in real time, show you where your leads are coming from and help you implement PPC, Adwords and Local Search campaigns optimally. Call tracking will also help you select and invest in keywords to improve your search engine optimization efforts.

When you combine the insights provided by both Google Analytics and call tracking, you’ll get a complete view of how your digital marketing initiatives are performing.