Defunct VoIP service provider SunRocket is suing Vonage, claiming its rival used its subscriber list without paying for it.

When SunRocket was in its final throes, it was negotiating for Vonage to buy the list of 200,000 subscribers, but talks fell through.

Now the company appointed to liquidate SunRocket’s assets is suing Vonage for using the list, which was disclosed under a confidentiality agreement, according to published reports.

The list is one of the most valuable assets left from SunRocket, and Vonage’s use of it reduces its value, the liquidation company claims.

According to published reports, Vonage says it obtained the list legally.

Meanwhile, Verizon charged Vonage with violating several of its patents. A court ruled that Vonage did violate the patents and owes Verizon money, but the decision is under appeal.