Initiate T.38 switchover when acting as called party, regardless of FAX direction.

SendFAX() and ReceiveFAX() can be given options to indicate whether they should
act as the calling or called party; this mode should be used to decide whether
to initiate a switchover to T.38, not the direction that the FAX transfer will
take place.

(closes issue #16039)
Reported by: jamicque


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@223330 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_fax.c

@@ -377,8 +377,8 @@ static int transmit_audio(fax_session *s)
 							     .transcoding_jbig = 1,
 	};
 
-	/* if in receive mode, try to use T.38 */
-	if (!s->direction) {
+	/* if in called party mode, try to use T.38 */
+	if (s->caller_mode == FALSE) {
 		/* check if we are already in T.38 mode (unlikely), or if we can request
 		 * a switch... if so, request it now and wait for the result, rather
 		 * than starting an audio FAX session that will have to be cancelled