AT&T's launch of a complementary Call Protect service for its wireless customers is likely to be among the first such services as telecom operators get more serious about blocking robocalls, under pressure from the FCC.

AT&T's service is a complementary offering to its wireless customers who also have HD voice. It's designed to block calls from known bad sources and provide a fraud warning to possible bad calls to alert its wireless customers.

Multiple vendors are now stepping up with options for network operators that want to get ahead of the machine-generated calling programs that are always annoying and sometimes the mark of scammers.

Transaction Network Services Inc. (NYSE: TNS) and its Cequint subsidiary are providing Sprint Corp. (NYSE: S) with a new service that uses network analytics to assign reputation scores to phone numbers and proactively block robocalls. Last week, Metaswitch Networks announced it is providing more than 20 service providers, including Pioneer Telephone Cooperative Inc. , with its anti-robocall solution. The solution combines a global database of blacklisted numbers with threat-detection algorithms that use data, including geolocation, call volume and historical trend data.

Both approaches create a database of phone numbers that have generated suspicious activity, and apply other network intelligence to let service providers offer robocall blocking as a network service. Today, most services that block calls, such as Nomorobo, a free third-party option, require the consumer to take action, entering their phone number into the service to get robocalls blocked.

TNS -- which operates massive databases for the US SS7 network and services such as local number portability and call routing across carriers -- saw an opportunity to use the network itself to identify robocalls, based on calling trends.

"We collected and analyzed data for the purposes of looking at fraud across the network, and we started seeing weird stuff," says Paul Florack, vice president of product management at TNS. That included queries to its databases for numbers that didn't exist or weren't assigned and very high query volumes from a number -- often a wireless number -- at a much faster pace than real calls could be made.

TNS also had enterprise customers who were interested in identifying when calls came in from spoofed numbers -- numbers which may or may not be real/assigned but are being used by someone who doesn't own the number to appear to originate a call.

"As we got into it deeper, we realized the extent of the issues," Florack says. "Our carrier customers were processing calls needlessly, and many of these calls were part of active scams."

Scam artists use the robocalling process to generate a massive number of calls that appeared to come from the US Internal Revenue Service or Treasury Department, for example, and try to extort money from those who answered.

The Federal Communications Commission has been pressuring telecom operators to crack down on robocalls leading to an AT&T-led strike force launched four months ago.

"This is a consumer-driven effort," notes Joe Weeden, vice president of product management at Metaswitch. "The FCC was fielding 300,000 complaints a month about robocalls."

Metaswitch developed a cloud-native microservice, running in the Amazon Web Services cloud to which its existing softswitch customers can point their switches to enable the robocall-blocking option.

"When a call comes into the customer, it hits our switch. We then call out to the robocall microservice for a lookup against the reputation-based database, which matches the blacklist number and blocks the call," Weeden explains. "The consumer doesn’t have to do any set-up at all."

The database is being constantly updated via network analytics and other means. Pioneer had its service up and running within a matter of weeks. There is an ongoing cost to support the service, and Weeden expects most of his customers will charge a nominal monthly fee to cover those costs, but some may choose to offer it at no cost.

The TNS approach is more involved, as the company is constantly updating a database of reputation scores for phone numbers that fluctuate based on real-time activity in the network.

The real-time aspect is essential, Florack notes, because the companies employing robocalls are constantly churning through numbers that are spoofed, and even using valid consumer numbers for some of their calls. It is also important to distinguish bad robocalls from "good" robocalls -- the ones that come from local governments or school districts to provide emergency alerts or other useful information.

TNS sells its anti-spoofing services directly to enterprises but the carrier-grade version it offers is intended for network operators to white label and deliver to their customers.

— Carol Wilson, Editor-at-Large, Light Reading