T-Mobile initially blocked VOIP service over its handsets but has since supported it. Unlike Vodafone and Orange, the U.K. subsidiary of German telco Deutsche Telekom doesn't block customers from installing and using mobile VOIP services such as Fring on its phones, according to Marks. "We're fully supportive of VOIP service."
Although Vodafone continues to terminate Truphone calls on its mobile network and pay the VOIP operator to complete Vodafone calls on its Wi-Fi network, the U.K. mobile phone operator isn't rushing into VOIP.
In an earlier statement, the company said it believes that VOIP over mobile is not yet a mature service and doesn't have guaranteed quality of service.
Vodafone is reluctant to talk about VOIP over mobile networks.
Analyst Cunningham agrees with quality of service concerns but argues that all mobile operators will nevertheless have to embrace VOIP because, he said, "it isn't going away."
He expects many operators to lower their voice tariffs to make them competitive with VOIP and also offer high-speed mobile and/or wireless broadband services as part of a multiservice strategy to lock them into one billing relationship.