[Freeswitch-users] SpanDSP: Timed out waiting for initial communication

Hello, I've got a fax service used to send an outbound faxes to lot of receivers. Sometimes I get "Timed out waiting for initial communication". What does it mean? Have freeswitch connected to the other end, but no fax tone is detected? Or something else? Should I retry again or remove the receiver from the list? Thanks, Jonas