This disclosure deals with an apparatus in a base station for controlling transmission of delay-sensitive data from a transmitter over a transmission link in a packet data communication network, which transmitter is capable of changing between a TTI bundling enabled mode and a TTI bundling disabled mode. The apparatus comprises: a receiver for receiving data from the transmitter over the transmission link; a decision unit for deciding that the transmitter should change TTI bundling mode; a silent mode detection unit for detecting that the transmitter is in the silent mode; and a triggering unit for triggering change of TTI bundling mode in response to deciding that the transmitter should change TTI bundling mode and in response to detecting that the transmitter is in the silent mode. The disclosure further relates to a corresponding method.