Models for Calculating the Reliability of IMS Operation When Introducing New Services on the Mobile Operator’s Network

Today, Ukraine is actively working to implement 4G and 4.5G technologies on networks of mobile operators. However, due to inaccuracies in forecasting the development trends of this type of networks, a situation has arisen whereby 2G and 3G networks will be used to service all voice traffic for a long time. As the research results show, one of the necessary conditions for the normal functioning of networks of mobile operators is the introduction of IP Multimedia Subsystem (IMS) as the main element of the management level. One of the main requirements for the IMS system is the requirement for the reliability of its operation. Since the requirements for reliability are very high, their fulfillment is impossible without the use of reservation methods. Therefore, the paper discusses possible reservation methods for the IMS system. The main elements of the IMS system were determined, models for assessing the reliability of operation with various reservation methods were developed, and a comparative assessment was made.