diff --git a/src/aprsis2.c b/src/aprsis2.c
index 5213cfb..30867b9 100644
--- a/src/aprsis2.c
+++ b/src/aprsis2.c
@@ -501,20 +501,31 @@ static int is2_in_parameter(struct worker_t *self, struct client_t *c, IS2Messag
 		goto done;
 	}
 	
-	hlog(LOG_INFO, "%s/%s: IS2: Parameter set received: request_id %ul",
-		c->addr_rem, c->username, par->request_id);
+	hlog(LOG_INFO, "%s/%s: IS2: Parameter set received: request_id %d%s",
+		c->addr_rem, c->username, par->request_id,
+		(par->filter_string) ? "filter_string" : "");
+	
+	/* prepare reply message */
+	IS2Parameter prep = IS2_PARAMETER__INIT;
+	prep.type = IS2_PARAMETER__TYPE__PARAMETER_FAILED;
+	prep.has_request_id = par->has_request_id;
+	if (prep.has_request_id)
+		prep.request_id = par->request_id;
+	IS2Message rm = IS2_MESSAGE__INIT;
+	rm.type = IS2_MESSAGE__TYPE__PARAMETER;
+	rm.parameter = &prep;
 	
 	if (par->filter_string) {
 		filter_set(c, par->filter_string, strlen(par->filter_string));
+		
+		prep.type = IS2_PARAMETER__TYPE__PARAMETER_APPLIED;
+		prep.filter_string = c->filter_s;
+	} else {
+		hlog(LOG_WARNING, "%s/%s: IS2: PARAMETER_SET: No parameters found for setting",
+			c->addr_rem, c->username);
 	}
 	
-	/*
-	if (ping->ping_type == KEEPALIVE_PING__PING_TYPE__REQUEST) {
-		ping->ping_type = KEEPALIVE_PING__PING_TYPE__REPLY;
-		
-		r = is2_write_message(self, c, m);
-	}
-	*/
+	r = is2_write_message(self, c, &rm);
 	
 done:	
 	is2_message__free_unpacked(m, NULL);
diff --git a/tests/libperl/Ham/APRS/IS2.pm b/tests/libperl/Ham/APRS/IS2.pm
index 44b5495..21fdf88 100644
--- a/tests/libperl/Ham/APRS/IS2.pm
+++ b/tests/libperl/Ham/APRS/IS2.pm
@@ -356,11 +356,13 @@ sub set_filter($$)
 {
 	my($self, $filter) = @_;
 	
+	my $reqid = int(rand(2**30));
+	
 	my $im = IS2Message->new({
 		'type' => IS2Message::Type::PARAMETER(),
 		'parameter' => IS2Parameter->new({
 			'type' => IS2Parameter::Type::PARAMETER_SET(),
-			'request_id' => 1, # todo: sequential
+			'request_id' => $reqid, # todo: sequential
 			'filter_string' => $filter
 		})
 	});
@@ -369,7 +371,40 @@ sub set_filter($$)
 	$self->is2_frame_out($im->encode);
 	$self->{'sock'}->blocking(0);
 	
-	return 1;
+	my $t = time();
+	while (my $l = $self->is2_frame_in()) {
+		my $rep = $l->parameter;
+		if ($l->type == IS2Message::Type::PARAMETER()) {
+			if (!$rep) {
+				$self->{'error'} = "PARAMETER type, but no parameter message";
+				return 0;
+			}
+			
+			if ($rep->request_id != $reqid) {
+				$self->{'error'} = "PARAMETER reply, wrong request id " . $rep->request_id . ", expected $reqid";
+				return 0;
+			}
+			
+			if ($rep->type != IS2Parameter::Type::PARAMETER_APPLIED()) {
+				$self->{'error'} = sprintf("filter set reply: not applied");
+				return 0;
+			}
+			
+			# todo: check sequence
+			return 1;
+		} else {
+			$self->{'error'} = "Wrong type of response received for PARAMETER_SET: " . $l->type;
+			return 0;
+		}
+		
+		if (time() - $t > 5) {
+			$self->{'error'} = "parameter command timed out";
+			return 0;
+		}
+	}
+	
+	$self->{'error'} = "No PARAMETER_APPLIED received";
+	return 0;
 }
 
 sub is2_frame_out($$)