The telephone is an excellent source of asynchronous events — you never know when it is going to ring. This means that web-based views of the telephony space make for interesting applications of Ajax Push.
Using SailFin and ICEfaces we've put together a very simple call setup demo. It shows when your phone is online and allows you to initiate a call between any two phones just by selecting them and pressing "call".
To run the demo:
java -Xmx512m -jar sailfin-installer-v1-b36-darwin.jar cd sailfin ant -f setup.xml bin/asadmin start-domain domain1 bin/asadmin start-database cp callsetup.sar domains/domain1/autodeploy/
As phones connect and disconnect, the list in the registrations page will be dynamically updated, showing user presence.
The full source code is available at http://anonsvn.icefaces.org/repo/projects/CallSetup/