In areas with both GSM and UMTS coverage, the GSM network can dynamically share its spectral resources with the UMTS network based on the service load on both networks. This sharing mechanism improves spectral efficiency. When the service load on the GSM network is below a specific threshold, some of the idle GSM spectral resources can be shared with the UMTS network. When the service load on the GSM network is above a specific threshold, the GSM network reclaims the shared spectral resources. UMTS has higher spectral efficiency than GSM. Therefore, GSM and UMTS Dynamic Spectrum Sharing (DSS) increases network throughput and reduces the composite costs of data services.

If some GSM sites that can share spectral resources with UMTS sites cover continuous areas, these areas form a spectrum sharing region, and these GSM sites act as a whole when sharing or reclaiming spectral resources.