Nokia has launched a tool that allows Nokia N80 phone users to make VoIP over Wi-Fi calls via SIPphone's Gizmo service. The company is offering a feature on the phone that lets users download a file that configures the VoIP settings to easily enable the use of Gizmo.

Gizmo customers can call each other for free although N80 Gizmo users could incur costs for accessing Wi-Fi networks. SIPphone also offers free calling to landline phones in some countries.

Nokia also recently introduced support for Skype VoIP calls on its N73 phones for customers who subscribe to an upcoming offering from 3 Group, the operator owned by Hutchison Whampoa. That offering uses the 3G (third-generation) network, rather than Wi-Fi.

While end users might be pleased with such offerings, which can allow them to save on their mobile phone bills because they enable free or low-cost calling, operators have typically been reluctant to enable the services. VoIP on mobile phones competes with the voice services that operators offer and also uses up network bandwidth that the operators might prefer to dedicate to more revenue-intensive offerings.

So while Nokia is introducing applications that help end users take advantage of Voip and other multimedia services, it's also trying to help operators ensure that customers don't use them extensively.

Last week, Nokia introduced Peer-to-peer Traffic Control, software that allows mobile operators to identify data traffic on their networks according to the type of service and then prioritise that traffic based on preferred services. That means operators can decide to make certain services, like VoIP, low priority so that if the network is full of traffic from more important services, the VoIP users won't get network access.

The traffic control product likely won't help operators hoping to control use of the Gizmo VoIP offering because that operates over Wi-Fi networks, which are typically owned by third parties or end users.

For more information, our sister site Techworld has a comprehensive VoIP resource page.