With the introduction of 4G and 5G, Communication Service Providers need to plan for 2G/3G closure to reuse the spectrum and reduce costs. This white paper provides recommendations on how to prepare for closure in the Circuit Switching and IP Multimedia Subsystem domains.

4G and 5G have enabled CSPs to gain access to new frequency bands and to re-farm the 2G/3G spectrum, allowing it to be used in a more efficient way. This results in more capacity and lower costs for mobile broadband. Energy efficiency and security are also improving as the transition from 2G/3G to 4G/5G is progressing.

The transition is expected to continue at a fast pace and many CSPs have already reached a VoLTE penetration exceeding 90 percent where it would be possible to retire both the 2G/3G networks for voice purposes. However, some challenges remain for these CSPs, such as IoT devices and emergency calls from vehicles (eCall) in the European Union (EU), preventing the final closure. Additionally, inbound roaming needs to be considered before closing a CSP’s own 2G/3G network.

to gradually replace 2G/3G is a long process, which can take more than 10 years. In addition to the introduction of IMS, the 4G/5G radio network needs to provide sufficient coverage and have voice services enabled and tuned. A sufficient base of VoLTE capable phones is also a prerequisite for replacing 2G/3G for voice services.