A method, implemented by a calling party's user terminal (UT-A), for placing a call from the calling party to a remote called party and a corresponding user terminal (UT-A). If the calling party's user terminal (UT-A) is available to access a packet data network (30), the call is established with the called party's user terminal (UT-C) over the packet data network. If the calling party's user terminal (UT-A) is not available to access the packet data network (30), a third-party user terminal (UT-D) available to relay the call is identified, communication with the third party is established via an alternative network, and the third-party user terminal (UT-D) is requested to relay the call to the called party's user terminal (UT-C) via the packet data network (30).