Phone calls

Direct, real-time voice communication: Alexander Graham Bell's 1876 patent established the circuit for transmitting human speech across the Public Switched Telephone Network (PSTN).

This technology is the backbone of instant, two-way voice communication. It converts your analog sound waves into electrical or digital signals (VoIP) for transmission across a vast network. The connection is initiated by dialing a unique address (a 10-digit number like 555-0199), which a central exchange routes in milliseconds. From Bell's first successful transmission in 1876 ("Mr. Watson, come here") to today's global fiber-optic and cellular networks, the core function remains: bridging any distance for immediate, clear conversation.

https://en.wikipedia.org/wiki/Telephone