== Starting Modem[i4l]/ttyI0 at default,0,1 failed so falling back to exten 's'
    -- Executing Dial("Modem[i4l]/ttyI0", "SIP/10|20|tr") in new stack
    -- Called 10
    -- SIP/10-b572 is ringing
Sep 21 17:40:32 NOTICE[7028]: channel.c:1758 ast_set_write_format: Unable to find a path from unknown to slin
    -- /dev/ttyI0 was hung up on before we answered
  == Spawn extension (default, s, 1) exited non-zero on 'Modem[i4l]/ttyI0'
    -- Hungup 'Modem[i4l]/ttyI0'