Every day more telephone conversations take place over wireless phones. Along with the convenience and mobility have come troubling privacy issues. Just how secure are the records of those calls?

The issue has moved to the front burner for some privacy advocates after the Chicago Police Department reportedly warned its officers their cell phone records are available for anyone who wants to buy them. Several online services are said to be the source of the lists of calls, available to anyone willing to pay the price.

The Chicago Police Department has launched an investigation of the purported sales, according to a report in the Chicago Sun-Times. The newspaper said law enforcement officials are concerned because criminals who obtained the call lists could possibly identify informants and undercover officers.

Privacy advocates have concerns as well, pointing out that employers could snoop into the private phone records of employees to learn who they have been calling regularly.

Locatecell.com, one of the companies reportedly cited by the Chicago Police, advertises a number of services on its Web site, including a reverse cell phone number look up service for $65 and a cell phone call record for $110.

"Give us the name and any combination of address or SSN and we will send you the working cell phone number," the company promises.

Some members of Congress are pushing for legislation to tighten controls, arguing the data is, in most cases, not obtained through lawful means. Investigators say, in some cases, telephone company insiders secretly sell customers' phone-call lists to online brokers.