Major carriers and app developers are ramping up their tactics for tackling robocalls on the iPhone and Android devices.

Some 5.51 billion robocalls were made in March 2019 in the US, according to data from a tracker published by Robokiller, a company that offers a robocall blocking app. “That's nearly 22 spam calls for every person,” Robokiller says.

Here are some of the best apps from carriers and app vendors – both free and paid as of spring 2019.

Verizon: Late last month Verizon rolled out a free robocall blocking app, which, among other features, offers spam detection and a spam filter.

THE 7 TECHNOLOGICAL WONDERS OF THE 21ST CENTURY

Verizon had already been offering a paid version for $2.99 per month. The paid app offers additional features such as Caller ID and a personal block list.

“Customers can choose to take advantage of the free solution or opt in to the enhanced caller name identification tools and spam lookup as part of the premium option,” a Verizon spokesperson told Fox News.

AT&T: The major carrier offers both a free app and a version that costs $3.99 per month. The free version blocks calls from suspected fraudsters, flags spam calls, and offers a personal block list.

The paid app adds features such as more detailed Caller ID reports and the ability to send unwanted calls to voicemail and block calls by entire categories.

HACKERS CAN TAKE OVER HEART DEVICES, DHS WARNS

Like other carriers, AT&T has “in-network systems that already label or block billions of unwanted or illegal robocalls,” an AT&T spokesperson told Fox News in an email.

The next plan of attack: STIR/SHAKEN

Verizon, AT&T and other carriers also working on a new authentication technology called STIR/SHAKEN (STIR stands for Secure Telephone Identity Revisited and SHAKEN for Signature-based Handling of Asserted information using toKENs.)

This tech will help consumers verify if an incoming call is really coming from the number listed on the caller ID display.

“While authentication won’t solve the problem of unwanted robocalls by itself, it is a key step toward giving customers greater … control over the calls they receive,” AT&T and Comcast said in a joint announcement last month.

WE'RE ALREADY IN THE MIDDLE OF A MAJOR CYBER WAR, EXPERTS BELIEVE

Other apps

Robokiller, Hiya, and Nomorobo are all robocall blocking apps for the iPhone and Android.

These apps offer the basic essentials such as advanced Caller ID, the ability to block calls that are “spoofed” to look like they are coming from a local number, and personal block lists. The apps typically offer a free trial period then ask for a small monthly fee.

Robokiller, for example, offers a personal list of allowed and blocked callers and so-called “Answer Bots,” which gives robocallers/telemarketers a “taste of their own medicine.”

Hiya, another app provider, has partnered with carriers and phone makers so it brings that experience to the table. For example, Samsung Smart Call has been powered by Hiya Client.

CLICK HERE TO GET THE FOX NEWS APP

Nomorobo has been around a long time and received plenty of accolades in the past. So this app is also worth a try.

Free "nuclear" option

Typically with these apps, some robocalls will still get through. So, a free way to stop robocalls cold is to turn on the “Do Not Disturb” feature on the iPhone or Android. But make sure contacts are excepted. In other words, toggle on "Allow Calls From All Contacts" (iPhone) when you use Do Not Disturb so calls from family, friends, and business contacts get through.