A method of transmitting a service to several subscribers in a packet data network capable of individual and group transmissions. The method includes collecting requests for the service from the several subscribers, evaluating the popularity of the service, forming a group of the subscribers that have requested the service, and transmitting the service over a group transmission if the popularity of the service at least equals or is likely to equal a predetermined threshold level. The mobile node subscribers may be reached via several different access networks, in which case an optimal access network can be selected. The method is preferably implemented by a group forming unit which can be integrated or co-located with a gateway which connects the service provider's network with the Internet.