A method for verifying compliance of a communication device with one or more requirement specifications is disclosed. The method comprises establishing a link between a test system and the communication device, wherein the establishing comprises configuring two or more bearers, one or more control channels, and one or more uplink packet filters; closing a test loop comprising the test system and the communication device, wherein the closing comprises activating a test loop function of the communication device; sending units of data associated with different service data flows in a downlink of the test loop from the test system to the communication device, each of the units of data including information representing the service data flow associated with the unit of data; receiving the units of data at the communication device; transferring the units of data to an uplink transmission arrangement of the communication device; and verifying, at the test system, that each of the units of data is transmitted, by the communication device in an uplink of the test loop to the test system, on a correct bearer corresponding to the service data flow associated with the respective unit of data according to the one or more uplink packet filters. Corresponding test system and test loop function arrangement are also disclosed.