Per-second billing for mobile voice and data will become a thing of the past as operators are forced to deliver all-you-can-eat fixed-price packages, industry experts predicted today.

Joel Stradling, a senior analyst at Current Analysis, told delegates at the NetEvents symposium in Evian today that the industry's move towards next-generation 4G mobile data services would sound the death knell for traditional usage-based billing, despite the fact that it would hit profits hard.

"Mobile operators are not keen on offering always-on single-priced flat-rate services but I think it is inevitable for the future," he said.

Stradling added that voice is likely to remain the "killer application" for mobile services in the future, but that traffic will be delivered as Voice over IP via services such as Skype.

"Voice will carry on as the killer app for IP telephony voice," he said.

Vivek Khuller, founder, president and chief executive at Divitas Networks, added: "The laptop has already converged, and mobile phones are in the process of converging.

"Laptops and cell phones will be pre-equipped with Wi-Fi or WiMax so that part of the device can remain under the control of the enterprise and the users can use cellular if they desire to do so. Voice will continue to be the killer application."

However, Stradling warned that usage profiles would change markedly with the move to 4G, creating serious challenges for mobile operators.

The analyst predicted that the volume of bandwidth required for the delivery of mobile services will ramp up exponentially as the industry moves to al ways-on pricing as users will leave VoIP connections open indefinitely.

This view was endorsed by Rob Bamforth, principal analyst at Quocirca, who observed that younger users of mobile services are increasingly embracing an "open mike" culture.

"Communication is becoming less of an event as we move to an always-on, always-connected world where communications channels are constant," he said. " The open mike culture will continue to grow."