The primary reason why 5G voice services typically require internet connectivity is due to the architecture of modern telecommunications networks.

1. VoLTE (Voice over LTE): With the transition to 4G LTE networks, voice calls started to be transmitted as data packets rather than traditional circuit-switched calls. This enabled higher quality calls and better integration with data services. Similarly, 5G networks continue to use VoLTE for voice calls, which means voice calls are treated as data packets over an IP (Internet Protocol) network.
2. Integration of Services: Telecom operators have integrated voice and data services into a single network infrastructure to optimize efficiency and provide a seamless user experience. This integration allows for features like simultaneous voice and data usage, HD voice quality, and faster call setup times.
3. Efficiency and Spectrum Utilization: By using VoLTE over 5G networks, telecom operators can efficiently utilize their spectrum resources. It allows them to allocate more bandwidth dynamically between voice and data services based on demand, which enhances network efficiency and performance.
4. Future-Proofing: As networks evolve towards all-IP (Internet Protocol) infrastructure, integrating voice over data networks ensures compatibility and future-proofing of the network for upcoming technologies and services.

While it’s technically possible to separate voice calls from data on a 5G network, current implementations and standards are geared towards VoLTE, which requires an internet connection. This integration not only improves service quality but also aligns with the broader trend towards IP-based communication systems.