TringMe's fully web-based SIP phone. A complete phone accessible from the browser.
TringMe's Push-n-Talk widgets are the simplest ways to stay "voice reachable" directly from the web.
Use Google Talk to make and receive calls. Making calls is as simple as sending a message.
Use data networks (WiFi, 2.5G/3G, GPRS) to make and receive calls, send and receive messages.
Use the web to activate a call but use your phone to actually carry out the conversation.
Leave voicemails easily throughout the world. Retrieve them via the web or get notified by email.