## 3 Results
### Subscriber Complaints Dataset  
Investigating customer complaints is one of the essential activities of customer-oriented organizations. Considering the competitive world among operators, it is necessary to manage customer complaints and adequately satisfy customers. The block diagram of the communication of subscribers' complaints with different departments of the mobile telecommunication company (first companion) is shown in Figure 17.  
After the customer communicates with the call center, the user report is separated from other calls based on the communication with the technical department. At this stage, complaints related to a similar incident are consolidated before being sent to the technical department and, finally, sent to the customer relations department of the technical department. The received reports in the technical department are re-checked and divided into categories, such as Voice, SMS, etc. Problems related to the  
Figure 17: Silhouette coefficient on idle mode scenario with 3 clusters. sites and the maintenance of BTS sites are sent to the Central General Administration of Tehran Province. After investigating the problem, the expert's report is transferred to the call center and the call center contacts the subscriber if necessary. The available data collection we used of to complaints from mobile telecommunication center subscribers related to technical problems, and was reported in October and November of 2020. The number of records of this data was 3200 in total. Table 8 below shows the features in this data. Among the reported problems by subscribers, temporary network disruption, echoing, receiving false messages during calls, coverage problems, disconnection, and antenna weakness were mentioned. The total number of these problems was divided into 6 general categories; about 80% of the reported issues was related to antenna and network coverage problems. This category's data was used to help better identify network faults, especially those not specified in the other two data categories. Therefore, by adding this information to the previous data, this information could be used to increase the accuracy of the proposed model. Our observations showed that about 1% of all calls raised as technical complaints to the mobile telecommunication company were unrelated to the technical department. The problem was related to the subscriber himself or herself, for reasons such as problem registration by non-technical personnel in the operator, as well as issues associated with the user, such as problems related to some types of mobile phones (for example, some mobile phones cannot support the AMR feature), wrong settings on the shared telephone (for example, call transferring to the wrong number), the existence of a hardware problem in the phone that led to poor quality audio, etc. Among the remaining 99% of complaints, about 35% of these calls stated problems were not worth taking any appropriate action, for technical and economic reasons. Calls were mostly related to the lack of antenna in remote areas or certain parts of a private house; for example, a user in a village with a relatively small population may contact the customer complaint center for lack of coverage in the network. Since there would be economic problems in installing a new site in that area, the mobile telecommunications company cannot take action to satisfy the customer. According to discussions with the experts, no specific action is taken to improve the network situation for this category of reports. Finally, 65% of the subscribers' complaints reflected a real problem in the network. It is important to note that all customer complaints should be investigated. After investigating a common complaint, according to the amount of other data available, such as performance support system data and field test data, appropriate actions are taken for that data if necessary.