An IP-based group communication feature in a mobile communication network is based on the pre-established logical connections established between a gateway node (GGSN) and members of a group in the mobile communication network. No separate call establishment procedures using VoIP signaling are used for connecting a user equipment (UE) logically to group(s), but the procedure is preferably based on the normal logical connection establishment signaling (e.g. PDP context creation) as used for data service. The UE implements a host supporting the IP multicasting, and the next IP layer peer for the UE host is located in the gateway node. The gateway node provides an IP interface towards an external multicast router so that the UE host looks like a normal IP host supporting IP multicasting. The IP-based voice traffic is mapped and transferred over pre-established connections between the gateway and the UEs of the specific group.