While working on gptg I wanted to be able to phone to the club by clicking on the tel link. To be able to do this I had to do the following in firefox:
  • open the about:config page
  • add the Boolean property network.protocol-handler.external.tel with a value of true
  • add the String property network.protocol-handler.app.tel with a value of /usr/local/bin/phone-call
And phone-call is a simple shell script that is calling twinkle my SIP client: 
#!/bin/sh

exec twinkle --immediate --call "`echo $1 | sed s/tel://`"

# phone-call ends here