[Freeswitch-users] mod_fifo ringall

Hello all! I have set up a queue with mod_fifo. I am trying to ring agents' phones all at once. I have looked at the wiki page http://wiki.freeswitch.org/wiki/Mod_fifo. Everything is working except that the phones are ringing one by one. I don't find the information to setup ringall strategy. I have done a Google search. It seems that it is possible but I don't find any information how to set it up. Can you help me with this? Fred