[Asterisk-Dev] Channel module question - setstate vs queue_control

[Bob Carlson]

I'm building a channel module and am wondering about the behavior of the *
channel code.  I've looked at several channel modules and it seems common
to this kind of thing:

ast_setstate(ast, AST_STATE_RINGING);
ast_queue_control(ast, AST_CONTROL_RINGING);

Are these redundant?  It would seem like sending the RINGING control would
change the state to RINGING or vice versa.  Are both actions necessary?

Is there a good description anywhere of these states and their behavior?  I
have looked at the wiki and several other places, but not found this info.

Bob