use the define for this

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@10098 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/switch_channel.c

@@ -1501,7 +1501,7 @@ SWITCH_DECLARE(switch_status_t) switch_channel_perform_mark_pre_answered(switch_
 
 		switch_log_printf(SWITCH_CHANNEL_ID_LOG, file, func, line, NULL, SWITCH_LOG_NOTICE, "Pre-Answer %s!\n", channel->name);
 		switch_channel_set_flag(channel, CF_EARLY_MEDIA);
-		switch_channel_set_variable(channel, "endpoint_disposition", "EARLY MEDIA");
+		switch_channel_set_variable(channel, SWITCH_ENDPOINT_DISPOSITION_VARIABLE, "EARLY MEDIA");
 		if (switch_event_create(&event, SWITCH_EVENT_CHANNEL_PROGRESS_MEDIA) == SWITCH_STATUS_SUCCESS) {
 			switch_channel_event_set_data(channel, event);
 			switch_event_fire(&event);
@@ -1649,7 +1649,7 @@ SWITCH_DECLARE(switch_status_t) switch_channel_perform_mark_answered(switch_chan
 		}
 	}
 
-	switch_channel_set_variable(channel, "endpoint_disposition", "ANSWER");
+	switch_channel_set_variable(channel, SWITCH_ENDPOINT_DISPOSITION_VARIABLE, "ANSWER");
 	switch_log_printf(SWITCH_CHANNEL_ID_LOG, file, func, line, NULL, SWITCH_LOG_NOTICE, "Channel [%s] has been answered\n", channel->name);
 	if ((var = switch_channel_get_variable(channel, SWITCH_CHANNEL_EXECUTE_ON_ANSWER_VARIABLE)) && !switch_strlen_zero(var)) {
 		char *arg = NULL;