Calculating the return on investment (RoI) of VoIP is a growing challenge for companies considering the technology, according the results of a survey from BT INS Inc., a consulting firm in Mountain View CA. Conducted earlier this year, the survey shows that "justifying costs versus benefits to upper management" tops the list of barriers to VoIP in businesses. It's also the barrier that has increased the most since 2005, BT INS said. Nonetheless, the number of organizations implementing or that have already implemented VoIP rose to 62% in 2007 from 44% in 2005. The three highest implementation objectives are increased network flexibility, lower administrative costs and simplified network infrastructure.