BorderWare has become the first company to license Zfone, the VoIP encryption software created and launched this summer by Phil Zimmermann.

The deal will see the software integrated with the company’s SIPassure VoIP Security Gateway product, best described as a do-it-all firewall with support for secure SIP-based VoIP sessions.

Zimmermann launched the beta version of Zfone as a free download for Macs and PCs earlier in the year. It is not a VoIP client as such, but is designed to work with third-party clients to provide the one thing Zimmermann has long said VoIP lacks – end-to-end security.

“As VoIP grows into a replacement for the PSTN, we will absolutely need to protect it, or organised crime will be attacking it as intensively as they attack the rest of the Internet today,” Phil Zimmermann was quoted as saying.

“VoIP is far more vulnerable to interception than the PSTN. Corporate VoIP calls can be captured and organised on disk for convenient point-and-click wiretapping by criminals half a world away.”

A major attraction of the product is that the encryption scheme used depends on a new protocol called ZRTP, which dispenses with the complexity associated with public-key management and the need for special servers. It works from client-to-client, handling encryption on a session-by-session basis between points using the same Zfone software.

“The combination of Zfone and BorderWare makes it easy to convert an entire installed base of office phones into secure phones in just one stroke, without having to replace them all with ZRTP-enabled phones,” he said.

Zimmermann is on record as saying that the model for Zfone will be to license the software after, hopefully, making it popular among influential users in the public domain. This week’s announcement shows the model coming to some fruition after an expensive development timeline.

He is in any case famous as the author of Pretty Good Privacy (PGP), the most prominent encryption software ever to hit desktop computing, which appeared in 1991. He has maintained his interest and expertise in the area ever since, despite becoming a sole trader some years back.