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No macro or processor named 'TracNav' found

The Broadband Phone Network

The DTG Broadband Phone Network is a thin-client device network consisting of one server and approximately 50 thin-client devices situated throughtout the lab (one per desk and a couple of common areas). The devices provide simple application (e.g. calculator), personalisation (e.g. contact lists) and VoIP functionality to other phones within the network.

System Overview

The system is structured in a client/server fashion. The server runs an embedded frame-buffer for each connected client which is synchronised with the client over a  VNC TCP stream. Likewise, input events (via the touchscreen) travel from client to server as feedback into application state. VoIP is standard SIP based signalling with RTP based audio transport.

Hardware

• Server(s): A standard x86 PC with 1GB of RAM running the server software

• Client(s): An ARM SA1100 based machine with 32MB of RAM, 8MB flash ROM, touchscreen, 16-bit sound card, 10Mbps ethernet running a modified version of the Linux kernel.

Software

Applications

• Server(s): The main server side component is a heavily modifed version of  Qtopia 1.7 running on a base of  QT 2.3.7. Coupled with this are a set of utility programs for connection, management and remote logging. Bindings are available for CORBA and in particular the Bat System.
• Client(s): Run a custom VNC client and some software to forward console logs to the server.

VoIP

• Server(s): Run the SIP Server with which all clients register. Does all VoIP maintenance, mainly:
  • Keeping track of registered phones:
  • Marking phones as offline [after prompting them to reregister]
  • Tracking phone calls
  • Inititating phone calls between clients

• Client(s): Run their own VoIP client and connect on a peer-to-peer basis for the duration of phone calls.

Synchronisation between clients and servers is maintained via the periodic exchange of control messages.

Papers

1. Ripduman Sohan, Andy Harter and Andy Hopper. TiCL: A Server Architecture For Thin-Client Networks. CUED TR-493. September 2004.  download

Hacking The Phone

For information on how to write applications for the phone, look here (local access required).