People love to say email will soon be dead, but marketers know that's far from true. Email remains one of the most effective channels for driving sales and building lasting relationships with customers.

Consider the following stats: Email has the highest ROI of any digital channel, raking in $38 for every $1 spent; 73% of marketers agree that email is core to their business; and more than 55% of marketers planned to increase their email marketing budget in 2016.

However, it's getting tougher to stay competitive. Marketers are in a continual battle to improve deliverability as well as open and engagement rates. Moreover, mobile has given rise to a new breed of customers who expect a one-to-one experience across all channels and devices, online and offline.

Accordingly, today's marketers are realizing email doesn't work in today's omnichannel landscape without a full picture of the customer journey—and that includes phone calls.

Email, meet phone calls

Calls are no more dead than email; in fact, they're on the rise. BIA/Kelsey estimates that by 2020 some 169 billion people will call businesses from their mobile phones.

But if you're blind to those crucial interactions, you can't deliver a relevant customer experience via email or any other point of engagement; worse yet, you can't measure true ROI or make informed decisions, because you have no idea what happens offline.

Call-intelligence technology brings a rich layer of customer data you need to deliver personalized emails that are seamlessly integrated with every part of the customer experience. Meanwhile, giving people the option to call directly from your email or landing page will boost engagement rates—especially with mobile users who would rather not do battle with tiny screens and online forms.

Here are three ways that phone calls can help you supercharge your email campaigns.

1. Your customers want to call, so make it easy

Customers want to call you. Why? Maybe they prefer human interaction. Or they have a question. Or they could be on the go, and a call is easiest. (Have you ever tried to fill out a long form with your thumbs?)

In today's omnichannel world, it's your job to give your customers the option to connect—however and wherever they want. Adding click-to-call numbers to your emails gives them the option to have a conversation when it's most convenient for them.

Make sure that your phone number is prominently displayed on all of your copy, with a clear call to action. Adding a phone number will only drive results if the number is easy to find. Fully 68% of mobile users will search for a number only for two minutes before moving on to another company.

2. Use call insights to improve personalization

Incorporating phone calls into your email marketing opens up a new world of targeting capabilities.

Consider this scenario: Someone calls to ask about a satellite TV package but isn't ready to purchase; he admits to the representative that he watches only sports channels. If you're using call intelligence, you can follow up with an email that's personalized based on certain words or phrases he said during the call. In this case, a promotional email for sports package would make perfect sense.

With call intelligence, you can also dramatically improve the data you have available to segment and personalize your email marketing campaigns at scale.

During the email opt-in process, you usually ask for one thing—an email address. If that same customer calls, and you're using call intelligence, you can capture dozens of additional data points, such as geographic location, age/gender, and household income, which you can then use to create audience segments and send hyper-targeted email campaigns.

3. Calculate true ROI

Proving ROI requires accurate attribution, and that's simply not possible without incorporating call data.

Have you ever launched a campaign you were sure would hit it out of the park, only to be disappointed with the results? It's possible that your numbers are low because you're not accounting for conversions that took place over the phone.

Call intelligence fills that blind spot by bringing call data into your email marketing dashboard, allowing you to track calls as accurately as you do clicks. In other words, you can prove your email marketing is a lot more valuable than you've ever could demonstrate before.

Your ROI will more accurately reflect the offline and online conversions that can be attributed to your email efforts, and you'll be able to optimize for the most successful omnichannel campaigns.

Here is the bottom line

Your customers expect a personalized and seamless experience. On the digital side, you're probably making great strides with doing so, but adding phone calls into the mix will enable you to drive much more value from email marketing.

It's time for email and phone calls to team up, and for marketers to embrace the fact that call intelligence technology brings the rich and varied layer of customer data we need to survive today's omnichannel world.

(For a deeper dive into the benefits of incorporating call data into your email marketing strategy, check out Invoca's step-by-step guide, Email, Meet Phone Calls.)