WASHINGTON (AP) — Federal authorities said Tuesday they’ve broken up a $1.2 billion Medicare scam that peddled unneeded orthopedic braces to hundreds of thousands of seniors via foreign call centers.

The Justice Department announced charges against 24 people across the U.S., including doctors accused of writing bogus prescriptions for unneeded back, shoulder, wrist and knee braces. Others charged included owners of call centers, telemedicine firms and medical equipment companies.

The Health and Human Services inspector general’s office said the fast-moving scam morphed into multiple related schemes, fueled by kickbacks among the parties involved. The FBI and 17 U.S. attorney’s offices took part in the crackdown. Arrests were made Tuesday morning.

Doctors would write prescriptions for orthopedic braces, regardless of whether the patients needed them or not.

Medicare said it’s taking action against 130 medical equipment companies implicated. They billed the program a total of $1.7 billion, of which more than $900 million was paid out.

Telemarketers would reach out to seniors offering “free” orthopedic braces, also touted through television and radio ads. Beneficiaries who expressed interest would be patched through to call centers involved in the scheme. Officials described an “international telemarketing network” with call centers in the Philippines and throughout Latin America.

The call centers would verify seniors’ Medicare coverage and transfer them to telemedicine companies for consultations with doctors.

“The telemedicine we are talking about is basically a tele-scam,” said Gary Cantrell, who oversees fraud investigations for the HHS inspector general’s office. “We are not talking about the use of advanced technology to provide better access to care.”

The doctors would write prescriptions for orthopedic braces, regardless of whether the patients needed them or not. In some cases several braces were prescribed for the same patient.

The call centers would collect prescriptions and sell them to medical equipment companies, which would ship the braces to beneficiaries and bill Medicare. Medical equipment companies would get $500 to $900 per brace from Medicare and would pay kickbacks of nearly $300 per brace.

The scam was detected last summer, officials said. Complaints from beneficiaries were pouring in to the Medicare fraud hotline, and some consumer news organizations warned seniors. As the investigation progressed, Cantrell said, federal agents gained cooperation from people familiar with the various schemes.

Officials said it’s one of the biggest frauds the inspector general’s office has seen. Charges were being brought against defendants in California, Florida, New Jersey, Pennsylvania, South Carolina and Texas.

Health care fraud is a pervasive problem that costs taxpayers tens of billions of dollars a year. The true extent of it is unknown, and some cases involve gray areas of complex payment policies.

Health care fraud is a pervasive problem that costs taxpayers tens of billions of dollars a year.

Experts say part of the problem is that Medicare is required to pay medical bills promptly, which means money often goes out before potential frauds get flagged. Investigators call that “pay and chase.”

In recent years, Medicare has tried to adapt techniques used by credit card companies to head off fraud. Law enforcement coordination has grown, with strike forces of federal prosecutors and agents, along with state counterparts, specializing in health care investigations.

The Medicare beneficiaries drawn into the orthopedic braces scam didn’t have to pay anything up front, but Cantrell said they have been harmed as well: A beneficiary’s private information, once in the hands of fraudsters, can be resold for many illegal purposes.

Additionally, if a beneficiary whose information was misused ever does need an orthopedic brace, he or she may encounter waiting periods from Medicare. The program limits how often it pays for certain supplies and equipment.

“It can be very attractive to receive equipment,” Cantrell said. “But after giving out your identifying information, it could be compromised to perpetuate additional fraud. There is no fraud without the ID number of a Medicare beneficiary.”