Vonage

(VG) - Get Report

may have violated federal securities laws in how it promoted its public offering, giving customers who are trying to get out of buying the shares a potential legal justification.

The problems, which were first disclosed by

Bloomberg News

, were outlined in filings the Holmdel, N.J.-based company made with the

Securities and Exchange Commission

on May 22 and May 23. Earlier this week, Vonage said it would hold people who bought shares through the Directed Share Program responsible for purchasing the stock that they were allocated.

Vonage, which experts acknowledge was facing potential lawsuits and possible regulatory scrutiny, made numerous errors in how it promoted the program, which was supposed to be a reward for customers. The company failed to provide a link to a prospectus when it established a special Web site for people interested in the allotment.

In addition, Vonage's initial voicemail communications to people about the share purchase program included details about a Web site where they could find additional information, but didn't say where a prospective investor could obtain a prospectus, the company says. Companies can't sell stock without a prospectus.

Vonage added that it would have meritorious defenses to any legal challenges and that the risks it faces because of the problems weren't significant. A Vonage spokesman couldn't immediately be reached for comment.

"We have urged potential participants in the Customer Directed Share Program to read this prospectus," Vonage says in the May 23 filing. "Neither the reading of this prospectus nor the accepting or acknowledging of any terms, conditions or other information set forth in this prospectus or on the Web site for the Customer Directed Share Program, however, relieves Vonage of any of its responsibilities or liabilities under U.S. securities laws or waives any rights that a participant has under those laws."

Shares of Vonage have continued to drop in the six days since they began trading. They are down about 31% from the IPO price, as investors bet that the continued bad publicity would drive Vonage customers to larger telecom, cable and Internet companies that are continuing to move into the broadband phone market.

It remains unclear how much trouble these revelations may create for Vonage. Companies that make errors in their public offerings, such

Google

(GOOG) - Get Report

, sometimes notify people that they have the right to rescind their purchases. That would require the company to repurchase the shares at cost, according to

Bloomberg

.

"One thing Vonage has to be considering is whether investors, if they are forced to pay, would have every incentive and motivation to go back over the details of how the IPO was conducted," University of Cincinnati Professor of Law Donna Nagy told

Bloomberg

. "If they could show that the law was violated, they could put shares back to the company."

Shares of Vonage last traded at $11.80. They were offered for sale at $17.