The invention relates to a method, a communication system and a switching apparatus which perform a switching of calls to another channel (CC2) when two or more calls simultaneously attempt to use a channel (CC1). According to the invention, each channel is first set (S3, S4, S5, S8) to a first call state when first attempting to use a channel. In the first call state, first predetermined transmission conditions must be satisfied (55) in order that the call proceeds to a second call state (S9, S10, S11, S14) in which second predetermined transmission conditions (S11) must be satisfied. Due to this progression of the call through a first, second and possibly higher order call states, it can be ensured that always a new call will always accomplish a hand-over to a new channel (CC2). The invention finds particular application when a channel may be used several times by several calls in a communication network of a channel re-use type and a substantial interferenceof the at least two calls occur when they use the same channel inclose proximity, e.g. when handing over a mobile telephone of a GSM system to a GSM-based cordless telephone system.