Spam robocalls have taken over the phone lines to an astonishing degree.

Modern technology has made the annoying practice easy and cheap, and by the middle of the year, robocalls are expected to make up half of all calls that occur in the U.S. Some companies are working on a plan to curtail robocalling, but it hasn’t appeared to help much yet.

According to new data from Transaction Network Services (TNS), which facilitates calls for small and large carriers, April 15 – tax day – will most likely be the worst day of the entire year for robocalls. Call volume was up 13% over last year, so this year may see similar gains.

The analysis, which processed over a billion calls across hundreds of carriers, found that tax season is generally the most dangerous time when it comes to robocalls. Last year, tax day had the most robocall volume, a whopping 143 million “nuisance and high-risk calls,” according to the data.

Some of them are scammers, and TNS expects that this year they will especially seek to take advantage of the confusion surrounding the government shutdown to prey on people leading up to tax day. You may have heard of them before, or know of someone who was duped by a caller claiming to be the IRS “demanding payment” or something like that. (The IRS will never call you as mode of first contact; instead they will send a bill in the mail.)

But not all. Some of them simply aim to take advantage of consumers in a more traditional marketing play, even if robocalls can be illegal. The study found that robocall volume has been up, but “high risk” scammy and fraudulent calls were actually down in 2018.

A few other key findings: Tuesdays are the worst, with 15% of all annoying calls, and Sunday had the least at 5%. While April is the worst month for robocalls, December is the best.

More robocalls came from Kansas City, Kan., than from any other place, and the south is the largest target. South Carolina, North Carolina, and Georgia had the most calls come in, and San Diego was the most robocalled-city and 706 in Georgia was the hardest-hit area code.

While it’s usually nothing more than a small annoyance to get a robocall, about one in 4,000 people will have their number hijacked by a “spoofer,” who uses that real number to place robocalls. When that happens, some people change their number.

Whether this will get any better is anyone’s guess. The industry, FCC, and FTC have been working for a long time on solutions to this intractable problem, but little relief has emerged as volume has mounted.

TNS’s chief product officer says the solutions are finally “on the horizon in 2019,” like technology that would act like a digital signature to make it impossible for spammers to steal people’s numbers — a big part of the problem. But until then, we wait and screen our calls.