Free Internet-based phone calls are the newest feature of the popular Kazaa file-sharing program.
The offering, in a software upgrade this week, comes as Kazaa's maker, Sharman Networks Ltd., faces increasing pressure to retain a user base eroded by rising competition from other file-sharing services and a full-court press by the recording industry.
Many of the computer users sued by the industry were using Kazaa, which was once regarded as the largest file-swapping community.
The main reason behind Sharman's foray into Internet-based phone service could be to prove that file-sharing technology has significant commercial uses other than as an unauthorized delivery system for copyright content, said Phil Leigh, senior analyst at Inside Digital Media.
That could help bolster Sharman against lawsuits brought by the entertainment industry in the United States and Australia.
Alan Morris, executive vice president of Sharman Networks in Sydney, Australia, denied any effort to legitimize Kazaa by adding Internet phone calling.
"The notion that we do something as major as that for any reason other than straightforward commercial reasons is no, absolutely not," Morris said. "There's absolutely no way, you go 'OK, this will be really good if they criticize us.'"
Internet-based phone calls travel in data packets online instead of being carried through analog telephone lines.
Sharman incorporated calling technology developed by Skype Technologies S.A., whose co-founders created Kazaa before selling it to Sharman.