Controlling establishment of a connection between an originating subscriber connected via an originating radio network to a communication network and a terminating subscriber connected via a terminating radio network to the communication network. The connection is established between originating payload node and terminating payload node employing a common coding scheme. Coding scheme negotiation comprises establishing, in originating control node (OCN), a list of supported coding schemes of originating subscriber, originating radio network and originating payload node. Determining, by the OCN, a radio channel property of the originating subscriber, oRCP, relaying the list and the radio channel property between the control nodes controlling the connection towards a terminating control node (TCN). Removing, by the control nodes, non-supported coding schemes from the list. Determining, by the TCN, common coding scheme(s) for the connection by selecting a remaining coding scheme considering the oRCP and a radio channel property of the terminating subscriber, tRCP.