(network planning) team is also concerned with the introduction and qualification of new features. At the end, it is worth noticing that with complication of networks (GPRS, EDGE, UMTS, Dual Band, etc.) basic optimisation steps need an automation process in order to give free time for more valuable tasks for the engineers. Statistics Network planning optimisation consists of various operations, all leading to the improvement of KPIs. In this section, statistic aspects are tackled and only general notions are presented. More details are given later. Each cell of the network should be operational intrinsically but also integrated in the network and interoperational with other cells. That is why two types of statistics are used to monitor: statistics on a cell level and statistics on an adjacency/area level. The same statistics can be extracted at a cell level or at an area level with some specific adaptation for each case. For example, the drop call formula for a cell will contain a number of handovers in the denominator. For an area level, handovers are considered as null except in area borders (in average a handover goes from one cell of the area to another cell inside the same area), which is why the drop call formula contains only a number of calls in the denominator. In fact, input data for starting optimisation are KPI values in a certain area. Depending an whether the area KPI is greater or less than the target, troubleshooting on a cell basis starts and statistics can be extracted weekly, daily or even on an hourly basis from the NMS. The call setup failure (CSF) and drop call rate (DCR) are the main KPIs relevant to operator losses. People who cannot access the network cannot call and then do not generate traffic and people who are dropped during a call are prevented from speaking more and generating more profit. These two rates can be computed according to various formulas according to what the operator wants to represent. In order to interpret properly and improve DCR and CSF values, other statistics sho