   #     res.event_json 'HEARTBEAT'
   #
   event_json: (events...,cb) ->
-    @send "event json #{events.join(' ')}", null, cb
+    @send "event json #{events.join(' ')}", cb
 
   # Remove the given event types from the events ACL.
   nixevent: (events...,cb) ->
-    @send "nixevent #{events.join(' ')}", null, cb
+    @send "nixevent #{events.join(' ')}", cb
 
   # Remove all events types.
   noevents: (cb) ->
-    @send "noevents", null, cb
+    @send "noevents", cb
 
   # Generic event filtering
   filter: (header,value,cb) ->
-    @send "filter #{header} #{value}", null, cb
+    @send "filter #{header} #{value}", cb
 
   filter_delete: (header,value,cb) ->
     if value?
-      @send "filter #{header} #{value}", null, cb
+      @send "filter #{header} #{value}", cb
     else
-      @send "filter #{header}", null, cb
+      @send "filter #{header}", cb
 
   # Send an event into the FreeSwitch event queue.
   sendevent: (event_name,args,cb) ->

    # and assign unified event IDs to the ESL Content-Types.

    switch headers['Content-Type']
      when 'auth/request'
        event = 'esl_auth_request'
      when 'command/reply'
        event = 'esl_command_reply'
        # Apparently a bug in the response to "connect"

#
# If you'd like to get realtime channel variables and synchronous commands, do
#
#     server = esl.createCallServer()
#
#     server.on 'CONNECT', (req,res) ->
#       # "verbose_events" will send us channel data after each "command".
#       res.command 'verbose_events', null, (req,res) ->
#         # You may now access realtime variables from req.body
#         foo = req.body.variable_foo
#         res.command 'play-file', 'voicemail/vm-hello', (req,res) ->
#           # Wait for the command to finish.
#           # The application continues here
#
#     server.listen 7000
#
# The asynchronous version of "command" is "execute".
#
# An asynchronous server will look this way:
#
#     server = esl.createCallServer()
#
#     server.on 'CONNECT', (req,res) ->
#       uri = req.body.variable_sip_req_uri
#
#     # Other FreeSwitch channel events are available as well:
#     server.on 'CHANNEL_ANSWER', (req,res) ->
