Nokia will begin shipping consumer voice over IP (VoIP) phones by 2006, but is claiming that the quality of some manufacturers' handsets may not be up to scratch.
Existing cellular phones are optimised for cellular voice communications, and tests on existing models showed that quality suffered during VoIP calls, in some cases significantly.
"I have tested Skype on mobiles and quality is lower than for voice calls," said Olli-Pekka Lintula, director of strategic marketing for technology platforms at Nokia.
"Today's handsets are optimised for cellular conversations. We do not see a quality benefit of VoIP over cellular on current handsets."
Lintula added that new handsets capable of switching the way they process the two types of voice call are needed if VoIP calls are to reach current cellular quality.
He also warned that the wireless networks in most offices were not ready for large-scale VoIP use.
Nokia is expecting that the bulk of VoIP traffic will initially take revenue from fixed line operators as consumers with DSL lines began to use VoIP and cancel their voice-only lines.
However, in the longer term, mobile operators will start to lose revenue to VoIP as well. Those operators relying on voice-only services will be particularly badly hit.
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