The registry started last week, but its operation had been turned over from the FTC to the Federal Communications Commission because of concerns that the FTC had overstepped its legal authority.
The 10th U.S. Circuit Court of Appeals said the FTC could run the registry while a challenge from telemarketers winds its way through the courts. Oral arguments were scheduled in Tulsa, Okla., on Nov. 10.
Some 50 million people have signed up for the free registry.
Late last month, U.S. District Judge Edward Nottingham of Denver had barred the FTC from putting the registry into effect because the list unfairly blocks calls from businesses but not charities.
In staying his ruling, the appeals court suggested that conclusion was too broad.
"The Supreme Court has held that there is undoubtedly a substantial governmental interest in the prevention of abusive and coercive sales practices," the court said. "The prevention of intrusion upon privacy in the home is another paradigmatic substantial governmental interest."
The court also noted that Congress had found some telemarketing calls "have subjected consumers to substantial fraud, deception and abuse."
Officials with the American Teleservices Association in Indianapolis declined immediate comment.
The free registry went into effect last week after the government scrambled to overhaul the system following the court challenges. The FTC gave up most control of the list to the FCC. President Bush also signed a hastily passed law giving the FTC authority to operate the registry.
It was Nottingham's ruling that had been closely watched because of the constitutional issues.
Attorneys for telemarketers argued the FTC has not shown charitable calls are less annoying than commercial calls. They also said the First Amendment rights of telemarketers need to be protected.
The list contains more than 50 million home and cell phone numbers. Companies could face thousands of dollars in fines each time they call a registered number.
"The main thrust came from the elderly who are home during the daytime and continually got badgered," North Carolina state representative Harold Brubaker, who sponsored the legislation, told CBS News Correspondent Peter Maer.