One startup benefiting from that burgeoning interest is Philadelphia-based Relay Network, which counts Cox Communications, Comcast (CMCSA), and Citizens Bank (CFG) among the big companies using its private messaging service with appreciable results.

Cox, for example, started using the Relay app in September 2015 to manage communications centered on upgrades by approximately 2 million people to its new digital video services. Customers who opt-in receive private, personalized notes related to their accounts, reporting on status and letting them know about related offers. The telecommunications company recorded a 40% reduction in recalls to its customer support team (compared with previous upgrade cycles) as well as 13% fewer field service visits, according to data shared by Relay.

Elsewhere, Citizens Bank (CFG) is using Relay’s app as part of an information service created to drive higher completion rates for student loan applications. The bank noticed that applicants were missing reminders that were sent via regular mail or left as part of voicemail messages. Since creating the “Citizens Bank Wire” service, Citizens has seen a 10% increase in the completion rate for its loans. Almost 85% of all applicants, especially millennials, use the service, according to Relay.

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Another example comes from insurance company Independence Blue Cross, which uses Relay’s messaging app to send information to approximately 300,000 people who subscribe to its health insurance policies. (At last count, the insurer had around 10 million members.) It adopted the system to help consumers select the most appropriate plans for their specific circumstances as well as to encourage them to use their benefits more proactively.

But it isn’t just millennials who have opted-in.

“We’re seeing more and more seniors who are using some type of Internet technology to get this information,” Independence Blue Cross president and CEO Dan Hilferty tells Fortune.

Relay Networks CEO Matt Gillin describes his company’s technology as similar to a “private Twitter feed” that can be personalized for a specific audience. “Our big idea is to establish a personal connection,” he says. “It is also bi-directional.”

So far, many of Relay’s early customers are using its app primarily to answer questions from new account holders, resolve billing questions, or to recommend new services to existing customers. It typically takes between 30 and 90 days to integrate Relay’s messaging system with a company’s existing customer service or communications channels, Gillin says.

Relay has raised about $28 million in backing, including a $12 million infusion in June 2016 that included Independence Blue Cross’ parent organization. In mid-November, the company added two new executives to its senior leadership team, a chief technology officer, and a chief product officer, who have experience selling business software and telecommunications services.

Most people communicate via text messaging.

There are dozens of startups catering to interest in messaging systems that help businesses communicate more efficiently with their own customers or, in other instances, with their employees.

Relay could find itself competing for mindshare against companies such as Intercom, an Irish-born startup that started its life selling chat apps for website that now has more than 13,000 customers; Helpshift, which helps customer support teams push messages into mobile apps; or Zinc, founded by two former Yammer (MSFT) employees, which focuses explicitly on helping companies communicate with workers in the field.