The development history of public network interphone is a process of continuous innovation and breakthrough. Since the beginning of the 21st century, with the rapid development of mobile communication technology, public network interphone has gradually emerged as a brilliant star in the field of wireless communication.

Initially, public network interphone developed based on China Telecom's base stations. Although it had a wide coverage, there were still some disconnected areas. However, with the continuous progress of technology, public network interphone has begun to achieve digitization and networking, greatly improving the quality and stability of communication.

In 2008, China initiated the formulation of the PMR (Professional Mobile Radio) standard, which promoted the interoperability and compatibility of public network interphones. Since then, public network interphones have gradually realized voice, video, data and other communication modes, with stronger functions and broader application fields.

In 2011, China began to promote TETRA (Terrestrial Trunked Radio) technology, which provided strong support for the digitization and networking of public network interphones with its efficient data transmission and secure encryption functions. By 2014, the introduction of LTE (Long Term Evolution) technology brought new development opportunities for public network interphones. Based on 4G network, LTE technology enables public network interphones to achieve high-speed data transmission and rich application functions, becoming a new favorite in the field of wireless communication.

In recent years, with the continuous development and application of 5G technology, public network interphones have also ushered in broader development prospects. The high speed and low latency of 5G networks will bring higher-quality voice and video communication experiences, and public network interphones will be able to provide clearer and more accurate voice instructions and image transmission. At the same time, public network interphones will further integrate and interoperate with other devices, providing more convenient and efficient communication solutions for various industries.

In summary, the development history of public network interphones is a process of continuous innovation and breakthrough. With the continuous progress of technology and the continuous expansion of application fields, public network interphones will play a more important role in the future.