stablishment reject mes- sage sent to the UE) and the UE moves to RRC idle state and RRC connection is released. For non-GBR (non-real time) calls these dropped calls do not have much impact on end-user experience due to the session setup but for, for example, voice over LTE (VoLTE) calls the end-user experiences muting as well as a dropped call. It should be noted that GBR or non- GBR calls can be re-established by new RRC and UE context setup through the target cell and if this is successful then the end users experience muting of voice or no throughput but no dropped calls. During the T311 running the UE tries to find a suitable cell according to the normal idle mode cell selection procedure [7] and if suitable cell is found the UE acquires system information messages and initiates transmission of RRC connection re-establishment message. In case the UE does not find any suitable cells and T311 expires the UE enters RRC idle state and RRC connection is released. In case timer T301 expires or selected cell is no longer considered as suitable cell, the RRC connection re-establishment procedure fails and the UE enters RRC idle state and releases the RRC connection. The E-RAB drop rate can be easily improved by tuning the timers T310 and T311 as well as out-of-sync, N310, and in-sync, N311, indications. However, it should be noted that any optimization of the timers and indication amounts above can cause increase of silent period, or the so-called mute time for VoLTE calls, when no data can be transmitted to the UE or received from the UE. Therefore, the duration of the silent period should always be considered when optimizing the timers and indication amounts. Typically the optimization is done in such a way that quite high amount of out-of-sync indication is needed before T310 timer is started (big N310) and detection of radio link failure is done fast, that is, short T310 with very small N311 to stop timer T310. With long (longer than T310) T311 value, the UE is allowed to try to find suitable cell and send the 