Communication · 12:30
Voice over the internet
Video calls, WhatsApp calls and online meetings all carry your voice as data. The first app to do that over the internet came from Israel in 1995.
The everyday moment
Your lunchtime call with a colleague in another country costs nothing and sounds clear, even on café Wi-Fi. Behind that is a problem every call app has to solve: the internet delivers data in bursts, out of order and sometimes not at all, while a voice has to arrive smooth and on time.
How it works
- Voice becomes dataYour microphone's sound is sampled, compressed and cut into small packets.
- Packets take different roadsEach packet travels across the internet on its own, so some arrive late, some out of order and some never.
- A short waiting roomA jitter buffer holds packets for a fraction of a second, puts them back in order and plays them at an even pace. Make it too long and the call lags, too short and it stutters.
- Hide what's lostMissing pieces are smoothed over so you hear a sentence, not a gap.
The Israeli story
Alon Cohen and Lior Haramaty founded VocalTec in 1985. The company first made audio products for PCs, including a sound card and a text-to-speech system for blind and visually impaired people in Hebrew and English.
In 1993 it moved to software and built VocalChat, for voice calls between computers on local networks. Then in February 1995 it released Internet Phone, the first app to carry voice calls over the internet.
Its core was the Audio Transceiver invented by Cohen and Haramaty, which kept latency low with a dynamic jitter buffer and handled lost packets, packets in the wrong order and mismatched audio rates. VocalTec listed on NASDAQ in 1996.
Where you meet it today
Voice over IP is now how most calls travel: in Zoom, Teams, WhatsApp and FaceTime, and inside phone networks themselves. The jitter buffer VocalTec built its product around is part of every one of them.
Did you know?
Before Internet Phone, VocalTec built a text-to-speech system that read Hebrew and English aloud for visually impaired users.