The disclosure relates a technique that allows one to identify communication sessions which are mistakenly detected as normally terminated from the network perspective. The first time period is used to monitor normal session releases initiated by a core network (CN) in respect of communication sessions for UEs. The second time period is used to check whether a Radio Link Failure (RLF) timer is already triggered at the time instant when the normal session release(s) is(are) detected by the RAN node within the first time period. If the RLF timer is already triggered, the number of the communication session(s) to be normally released based on the normal session release(s) from the CN is counted and reported to a network management system when the first time period expires. In response, the network management system properly optimizes RAN or other network parameters such that a call drop rate is improved.