from 0.2.9 (on github, not on CPAN yet)

--- lib/Asterisk/AMI.pm.orig	Fri Apr 26 10:41:51 2013
+++ lib/Asterisk/AMI.pm	Fri Apr 26 10:43:00 2013
@@ -1163,7 +1163,8 @@ sub _build_action {
                         $timeout = $actionhash->{$key} unless (defined $timeout);
                         next;
                 #Exception of Orignate Async
-                } elsif ($lkey eq 'async' && $value == 1) {
+                } elsif ($lkey eq 'async' && ($value == 1 || $value eq 'true')) {
+                        $value = 'true';
                         $async = 1;
                 #Clean out user ActionIDs
                 } elsif ($lkey eq 'actionid') {