PGPfone is a software for encrypted transmission of telephone calls over the Internet using the PGP process.
The program was developed by Phil Zimmermann, who is also the creator and programmer of PGP. It can be considered as a very early forerunner of today's VoIP.
According to the MIT, under whose participation this program was developed, it was no longer under development since 1997.
"MIT is no longer distributing PGPfone. Given did the software Has not been maintained since 1997, we doubt it would run on most modern systems. "
Currently, the software that is the source code and documentation, but are still based on the website of PGPI.ORG (see links).
Contrary to the expectation of the MIT, this program is still run even on Windows 2000 and Windows XP. From the usability and quality of speech here but it can not oppose more modern VoIP applications such as Skype.
In March 2006 Zimmermann presented, therefore, the beta version of a software developed from scratch before called Zfone to encrypt VoIP calls.