[Freeswitch-users] Howto setup BLF event lists?

Hi I am pretty new to all this, so bear with me. I have Grandstream phones running with my freeswitch setup. I would like to use the BLF which works via event lists. It seems that freeswitch supports this. However, I do not find any documentation how to setup such an event list. The only thing I know is where I need to enter the URL (whatever it may look like...) into the Grandstream. Can anybody hint me to some documentation? Thanks a lot Michael