GREELEY, Colo (CBS4) Aggressive and unwanted telephone calls are among the top complaints of consumers. About 75 percent of telephone users have their number on the National Do Not Call Registry, but still those unwanted calls keep coming.

Felicity Spring was fielding threatening calls every day.

“He said, ’Shut up…shut up…shut the f— up’,” Spring told CBS4.

The calls came several times a day, and all from the same number with a Michigan prefix. The caller ID indicated the calls were tied to credit cards. Online, dozens of people have posted complaints about these constant calls.

“It puts you in a victim circumstance,” Spring said.

Spring called the police, but they said they couldn’t help. So she called her phone company, and they were able to put a block on the number. Local phone companies have varying policies. But if the calls are frequent or threatening, they can set a trap on your phone line and find out where the calls are coming from. This service is free.

Some phone companies also has a service called Call Trace. Immediately after getting a call, you enter in “star-5-7” and the call is automatically traced. The Call Trace service does come with a fee. Spring’s phone company blocked the number for her, but her company puts a 12-number limit on the calls that can be blocked.

Technology is making it tough to trace these calls. Scammers can rout a call through multiple phone lines making it very difficult to track them down. If you get threatening phone calls, you can file a complaint with the Colorado Attorney General’s Office. They review all complaints and see what merits an investigation.
RELATED: More Reports By 4 On Your Side Consumer Investigator Jodi Brooks

– Written for the Web by CBS4 Special Projects Producer Libby Smith