# Speak Freely for Windows

by John Walker
http://www.fourmilab.ch/

### Contents

Speak Freely is a Windows Internet telephone application that allows you to talk (actually send voice, not typed characters) over a network. If your network connection isn't fast enough to support real-time voice data, various forms of compression may allow you, assuming your computer is fast enough, to converse nonetheless. To enable secure communications, encryption with DES, IDEA, and/or a key file is available. If PGP is installed on your machine, it can be invoked automatically to exchange IDEA session keys for a given conversation. Speak Freely for Windows is compatible with Speak Freely for Unix, and users of the two programs can intercommunicate. Users can find one another by communicating with a "Look Who's Listening" phonebook server. You can designate a bitmap file to be sent to users who connect so they can see who they're talking to. Speak Freely supports Internet RTP protocol, allowing it to communicate with other Internet voice programs which use that protocol; in addition, Speak Freely can also communicate with programs which support the VAT (Visual Audio Tool) protocol.

Introduction
  Hardware and software requirements

Quick Start Guide

Connections
  Creating a new connection
  Setting connection options
  Closing a connection
  Saving a connection in a file
  Opening a connection file

Communicating
  Receiving audio
  Sending live audio
  Sending sound files
  Ringing remote users
  Testing using local loopback
  Multicasting to a group
  Broadcasting to multiple sites
  Conferencing
  Viewing extended status
  Monitoring audio levels and spectrum
  Voice activated transmission
  Communicating with other network audio programs

The answering machine

Show your face

Text chat

Phonebook: Look Who's Listening
  Publishing your directory entry
  Finding on-line users

Compression

Encryption
  Why encryption?
  Varieties of encryption
  - AES (Advanced Encryption Standard)
  - PGP key exchange
  - DES (Data Encryption Standard)
  - Blowfish encryption
  - IDEA (International Data Encryption Algorithm)
  - Key file
  Generating and exchanging keys
  Legal issues
  Patent issues

Window display modes

Command line arguments

Problems, problems
  Regular pauses in audio output
  Random pauses in audio output
  Compression slows down transmission
  Viewing extended status
  Workarounds for driver bugs

Internet resources
  Speak Freely Internet mailing lists
  Echo servers
  Publishing your directory entry
  Finding on-line users

Debugging tools
  Viewing extended status
  Local loopback
  Remote echo mode
  Monitoring audio levels and spectrum
  Diagnostic console

Hardware issues
  Viewing hardware configuration
  Measuring computer performance
  8 or 16 bit sampling?
  Half- or full-duplex?

Bugs, features, and frequently asked questions

References
  Speak Freely for Unix machines
  Credits
  Bookshelf
  Development log
  About the author