telefoni

Telefoni, or telephony, is the field that covers the transmission of voice, data, and multimedia over distance using electronic devices and networks. It includes traditional public switched telephone networks (PSTN) as well as mobile, VoIP, and IP-based communications. Telephony relies on signaling, routing, switching, and measurement to establish and maintain connections between callers and deliver services.

The telephone was invented in the 1870s by Alexander Graham Bell, with rapid growth of wired networks and central offices in the late 19th and early 20th centuries. The mid-20th century brought automated switching and long‑distance networks; the latter part of the century introduced mobile and cordless telephony, digital technologies, and the beginnings of data transmission over telephone lines.

Modern telephony uses several core technologies. The traditional PSTN remains in use, often digitized, alongside ISDN and, increasingly, IP-based networks. Mobile telephony operates over cellular networks across generations (2G to 5G). Voice over IP (VoIP) converts speech into data packets transmitted over IP networks, commonly via SIP signaling and RTP streaming. Signaling systems include SS7 for legacy networks and SIP for IP-based ones.

Common devices include fixed telephones, mobile phones, and software phones (softphones) on computers. Services include caller identification, voicemail, call forwarding, conferencing, and number portability. Telephony also supports emergency services access. Privacy and security concerns include eavesdropping, spoofing, spam, and phishing, leading to ongoing efforts to enhance encryption and secure signaling.

Today telephony is increasingly integrated with the wider internet and enterprise communication tools. All-IP networks, cloud-based telephony, and unified communications platforms blend voice with video, messaging, and collaboration features. The trend is toward more flexible, software-defined architectures and global interoperability, while maintaining reliability and regulatory compliance across jurisdictions.