[Freeswitch-users] dtmf events outbound in 'freeswitcher' ruby library

Does anyone know how to get dtmf events in outbound with the freeswitcher ruby library. I see that in inbound 'FSL::Inbound.add_event_hook(:DTMF) {|event| dtmf_handler(event) ' can be used but how can it be done in outbound