In third generation mobile communications networks, e.g. CDMA systems, a mobile station intending to access a base station transmits a request for access to a base station and waits for a response in the form of an indicator signal. Both detecting a signal as an acknowledgement message without one being sent from the base station and failing to detect such an acknowledgement message can give rise to noise and interference in the whole cell. The invention provides a method and a user equipment for determining the received signal strength in an access slot in a downlink channel and for asserting whether detection of an indicator signal from the base station in the access slot in the downlink channel is reliable. Hereby, a more secure reception of indicator signals can be obtained, which leads to reduced interference and noise in the whole cell.