state_changed
Description:
public signal void state_changed (uint state, uint flags, CallStateReason reason, HashTable<string,Value?> details)
  
  The state_changed signal is emitted whenever the call state changes.
Parameters:
| state | the new CallState | 
| flags | the new CallFlags | 
| reason | the CallStateReason for the change | 
| details | additional details as a GenericSet readable using the tp_asv_* functions. |