One of the first secure telephony programs. Not limited to VOIP but can also directly encrypt a telephone line by using modems. Calls are encrypted using Diffie-Hellmann key exchange and several symmetric ciphers.
Download is possible from Germany only, see homepage
Echomine Muse provides an easy-to-use Java API that gives you quick and easy access to network collaboration services. Specifically, it allows you to communicate with Jabber/XMPP servers to perform instant messaging and presence management.