From what I understand based on the documentation at https://freeswitch.org/confluence/display/FREESWITCH/Lua+API+Reference#LuaAPIReference-session:setInputCallback you can pass an arg to the callback function in the second argument of session:setInputCallback, however in my callback if I have function my_cb(s, type, obj, arg) the value of arg is always nil, does anybody have this working or can confirm if the documentation is correct?