When your phone rings today, you probably shouldn't answer it.
Odds are high it will be a robocall — and you will probably get more than one of them in the next 24 hours. In fact, you may feel like you've gotten more of them than ever this year.
Robocalls, automated calls that usually have a recorded message, have pestered consumers for decades. But the call rate has accelerated this year, and that has left regulators, carriers and software companies working to land a fix.
"Every time my phone rings it interrupts the work I'm doing," said Hannah Donahue, a media strategist in Los Angeles. "Even if I don't answer the phone, it's disruptive."
Donahue, 31, said she gets about six robocalls a day, starting as early as 7 a.m. and continuing into the evening.
The calls are especially intrusive because she needs to keep her phone with her to field calls from clients, she said. And since she's stopped answering calls from unknown numbers, she occasionally misses an important business call.
Donahue said the frequency of calls increased this year. Data backs her up.
The number of robocalls placed nationwide increased 50 percent from February to July, according to data from YouMail, a company that provides voicemail and call-blocking services to iPhone and Android users.
Robo-dialed and unwanted telemarketing calls were the top consumer complaint to the Federal Communications Commission last year, and they are again this year. This puts those complaints ahead of billing disputes, service availability and program indecency.
Not all robocalls are bad. Some, like appointment reminders and flight updates, are usually welcome. But robocall scams, such as the wave of calls that targeted Chinese communities this spring, can be harmful. According to news reports, more than 30 consumers in New York City were tricked out of an estimated $3 million by callers pretending to be from the Chinese consulate and demanding money to settle a criminal matter.
According to YouMail, scams made up about 40 percent of the 4.4 billion robocalls placed to Americans in September.
Not all area codes are equal: Phone owners with a 404 area code (Atlanta) on average received 68 robocalls in September. That's much higher than the next-worst area code, 202 in Washington, D.C., which got an average of 49 robocalls the same month.
"It's definitely been building within the past five years, but it's gotten especially bad this year," said Ethan Garr, vice president of product for TelTech Systems, which makes the call-blocking app RoboKiller. Like YouMail, RoboKiller also saw a big increase in the number of robocalls this year.
Experts are divided about the cause of this year's sharp rise in calls. Garr said some of the calls may have been political solicitations in advance of midterm primaries. But YouMail CEO Alex Quilici told NBC News that he believes changing consumer behaviors have led scammers to try harder.
"The carriers started to identify the bad guys," Quilici said. "Call-blocking apps started to scale up and get publicity. What we figure is that bad guys started having to call more to get through."
The experts do agree on what's driving robocalls: technology. Several told NBC News that many websites and apps allow anyone to send robocalls, often at little expense.
"You can go to certain websites, put in your phone numbers, put in your audio, push a button and now you're annoying a city," Quilici said.
"Voice calls are so cheap, they cost only a penny a minute and [robocallers] pay for the calls that pick up," Garr said. "You're not limited by the number of calls you can make. You're limited by the number of people that can answer the calls."
In April, the Senate learned about the ease of robocalling when alleged robocall "kingpin" Adrian Abramovich testified before the Committee on Commerce, Science and Transportation.
The FCC fined Abramovich $120 million in May for placing nearly 100 million robocalls over a three-month period. In his Senate testimony, Abramovich told the committee that he found robocalling software and services by searching Google.
Abramovich also said many services provide a "neighbor spoofing" function, which makes automated calls appear to be coming from the recipient's area code.
"Spoofing is very easy," Abramovich told the committee. "You can do that in a day."
Abramovich did not respond to messages seeking further comment.
The FCC encourages consumers to let unknown calls go to voicemail, or to hang up on calls that ask them to press a button to stop receiving future calls. The FCC also recommends joining the National Do Not Call Registry, which prevents callers from being bothered by lawful telemarketers. But don't expect that to fix everything.
While the Do Not Call list will stop calls from legitimate businesses, experts said illegal callers have no problem ignoring the list.
"The vast majority of calls you are getting are scam calls or spam calls or businesses that aren't afraid of taking the risk," Garr said.
Mobile carriers and phone manufacturers have stepped up their efforts to fight robocalls as well.
The nation's four largest carriers, AT&T, Verizon, T-Mobile, and Sprint, all offer robocall-blocking services. Last week, Google unveiled a call-screening feature in its latest Pixel smartphone that will answer and transcribe robocalls. And the telecom industry is working on a technology standard, named Stir/Shaken, designed to authenticate phone numbers and make spoofing more difficult.
These kinds of technology improvements may eventually help solve the problem, Quilici said, drawing parallels to the fight against spam emails in the 2000s.
"It's actually true of email," Quilici said. "We still get a ton of spam, but Google and everyone has gotten so good at filtering email that you don't notice. The phone network hasn't gotten as sophisticated in the filtering."