A method for operating a communication device in a cellular radio system, comprising: in a random access procedure, sending to a network node device a first message including a random access preamble according to a Time Division Duplex, TDD, configuration in a system information block; and in the random access procedure, receiving from said network node device a second message including a random access response using said random access preamble according to said TDD configuration in said system information block; wherein said communication device is assigned multiple TDD configurations related to a cell served by the network node device before initiating the random access procedure, and said multiple TDD configurations include said TDD configuration in said system information block and further include at least another TDD configuration informed via dedicated Radio Resource Control signaling; wherein the random access procedure is a contention-based random access procedure, in the random access procedure, sending to said network node device a third message including an identifier specific to said communication device according to said TDD configuration in said system information block; and either: switching said communication device into a dynamic TDD capable mode to support a plurality of dynamic TDD configurations, and receiving from said network node device a fourth message including a contention resolution by monitoring downlink channels according to said plurality of dynamic TDD configurations; or: receiving from said network node device a fourth message including a contention resolution according to said TDD configuration in said system information block; and switching said communication device into a dynamic TDD capable mode to support a plurality of dynamic TDD configurations; wherein each of the plurality of dynamic TDD configurations has uplink subframes that belong to a subset of uplink subframes of said TDD configuration in said system information block and downlink subframes that belong to a subset of downlink subframes of said another TDD configuration informed via dedicated Radio Resource Control signaling. in a random access procedure, sending to a network node device a first message including a random access preamble according to a Time Division Duplex, TDD, configuration in a system information block; and in the random access procedure, receiving from said network node device a second message including a random access response using said random access preamble according to said TDD configuration in said system information block; wherein said communication device is assigned multiple TDD configurations related to a cell served by the network node device before initiating the random access procedure, and said multiple TDD configurations include said TDD configuration in said system information block and further include at least another TDD configuration informed via dedicated Radio Resource Control signaling; wherein the random access procedure is a contention-based random access procedure, in the random access procedure, sending to said network node device a third message including an identifier specific to said communication device according to said TDD configuration in said system information block; and either: switching said communication device into a dynamic TDD capable mode to support a plurality of dynamic TDD configurations, and receiving from said network node device a fourth message including a contention resolution by monitoring downlink channels according to said plurality of dynamic TDD configurations; or: receiving from said network node device a fourth message including a contention resolution according to said TDD configuration in said system information block; and switching said communication device into a dynamic TDD capable mode to support a plurality of dynamic TDD configurations; wherein each of the plurality of dynamic TDD configurations has uplink subframes that belong to a subset of uplink subframes of said TDD configuration in said system information block and downlink subframes that belong to a subset of downlink subframes of said another TDD configuration informed via dedicated Radio Resource Control signaling.