We offer an open library to support serverless VOIP phonecalls for Instant Messengers.

Currently we work to implement Tstone into our partnerprojects, which are Retroshare.sf.net Serverless Instant Messenger and (serverbased) Multimessenger SIM-IM.org

Other projects are appreciated to use as well our openphoning Tstone libraries with components of OpenH.323 and OpenSIP written in C++ and with QT4 gui.

T stone is NOT endorsed by or affiliated with SKYPE. We are opensource and serverless.

tstone.sourceforge.net  http://www.sourceforge.net
Chinese Version - English Version


Peer to Peer (P2P), Friend to Friend (F2F) and Voice over IP (VoIP) are currently two highlights in the field of international internet application technology - especially instant messengers. P2PVoIP is a combined P2P and VoIP system and recently is an important subject of internet technology. P2PVoIP has high performance in VoIP by using P2P high robustness and scalability.

Considering presently existent problems of VoIP, we analyse current P2P system’s advantages and use basic principle of P2P. This application library presents a general design framework for hybrid structured P2P IP software phone and we developed a prototype. Next step is to offer this library to our Instant Messenger partner projects.

In our work the disadvantages of current VoIP system are analysed, and current P2P system’s workflow and principle are compared, it results in an analysed and developed current P2PVoIP system in detail - called T stone library.

The achievements of this work are summarized as follows:

  • The general design framework for hybrid structured peer to peer IP software phone library. There is no centralized server and the network self-organizes itself. It change old VoIP system workflow and it have scalability, robustness, denial of service (Dos) attack and fault tolerance. System increases voice quality of local area network (LAN).
  • We developed a prototype of hybrid structured P2PVoIP software called tstone as a library. A Kademlia DHT was used to search for the other telephony participant. So the system does not depend on commercial servers and company’s maintenance. It will save a lot of money. It hasn’t single point of failure.
  • The system can connect to traditional H.323 VoIP system smoothly.
  • The tool can analyse runtime network status. We develop a tool that can be created a picture of network lost packages or latency to show all runtime network visual status report for user.


  • The carrier grade method for P2PVoIP. The major issue is how to control pay for service<br />
    workflow and make a good carried grade mode. We present a method that every P2P nodes increase principle of authentication and account base on Remote Authentication Dial In User Service (RADIUS) protocol. By this interface the carrier grade which want to use the P2P network, can join the P2P network as a part easily.