Wireless voice-over-IP poses a significant threat to cellular operators and likely could reduce their revenues, a study released Tuesday by U.K. market research firm Analysys claims.

In fact, decreasing cellular data prices could lead to use of VoIP over 3G networks, meaning that cellular operators will be losing voice revenues to themselves, the author of the study said.

"VoIP may look more attractive to those seeking to bypass mobile operators' voice tariffs, particularly if an opportunity to undercut those tariffs using VoIP arises due to significant falls in 3G data pricing," report co-author Dr. Mark Heath said in a statement. "A number of mobile operators have launched unlimited-use data tariffs that could make them vulnerable to customers using VoIP to cut their spend."

Besides using VoIP over the networks of cellular operators, VoIP also will be available via other types of wireless networks such as WiMAX and Wi-Fi, the study notes. In fact, VoIP could well strengthen the hand of technologies such as mobile WiMAX or FLASH-OFDM, according to the study.

"Wireless VoIP presents fixed operators, (wireless virtual network operators) and VoIP providers with opportunities to disrupt the mobile voice market," the study said.