diff --git a/tests/simulator-udp.pl b/tests/simulator-udp.pl
index fc99aeb38..c27bbbcec 100755
--- a/tests/simulator-udp.pl
+++ b/tests/simulator-udp.pl
@@ -6,15 +6,20 @@ use Socket;
 use UUID;
 use BSD::Resource;
 use Getopt::Long;
+use Socket6;
 
-my ($NUM, $IP) = (1000, '127.0.0.1'),
-my ($NODEL);
+my ($NUM, $RUNTIME) = (1000, 30);
+my ($NODEL, $IP, $IPV6);
 GetOptions(
 		'no-delete'	=> \$NODEL,
 		'num-calls=i'	=> \$NUM,
 		'local-ip=s'	=> \$IP,
+		'local-ipv6=s'	=> \$IPV6,
+		'runtime=i'	=> \$RUNTIME,
 ) or die;
 
+($IP || $IPV6) or die("at least one of --local-ip or --local-ipv6 must be given");
+
 $SIG{ALRM} = sub { print "alarm!\n"; };
 setrlimit(RLIMIT_NOFILE, 8000, 8000);
 
@@ -55,49 +60,78 @@ sub do_rtp {
 	print("sending rtp\n");
 	for my $c (@calls) {
 		$c or next;
-		my ($fds,$outputs) = @$c[0,4];
+		my ($fds,$outputs,$protos) = @$c[0,4,6];
 		for my $i ([0,1],[1,0]) {
 			my ($a, $b) = @$i;
-			send($$fds[$a], 'rtp', 0, sockaddr_in($$outputs[$b][0], inet_aton($$outputs[$b][1]))) or die $!;
+			my $pr = $$protos[$a];
+			send($$fds[$a], 'rtp', 0, $$pr{sockaddr}($$outputs[$b][0],
+				inet_pton($$pr{family}, $$outputs[$b][1]))) or die $!;
 			my $x;
 			my $err = '';
 			alarm(1);
 			recv($$fds[$b], $x, 0xffff, 0) or $err = "$!";
 			alarm(0);
 			$err && $err !~ /interrupt/i and die $err;
-			$x eq 'rtp' or warn "no rtp reply received, ports $$outputs[$b][0] and $$outputs[$a][0]", undef($c);
+			$x eq 'rtp' or warn("no rtp reply received, ports $$outputs[$b][0] and $$outputs[$a][0]"), undef($c);
 		}
 	}
 }
 
+my %proto_defs = (
+	ipv4 => {
+		code		=> 'I',
+		family		=> AF_INET,
+		reply		=> '4',
+		address		=> $IP,
+		sockaddr	=> \&sockaddr_in,
+	},
+	ipv6 => {
+		code		=> 'E',
+		family		=> AF_INET6,
+		reply		=> '6',
+		address		=> $IPV6,
+		sockaddr	=> \&sockaddr_in6,
+	},
+);
+my @protos_avail;
+$IP and push(@protos_avail, $proto_defs{ipv4});
+$IPV6 and push(@protos_avail, $proto_defs{ipv6});
+
 for my $iter (1 .. $NUM) {
 	($iter % 10 == 0) and print("$iter\n"), do_rtp();
 
 	my $callid = rand_str(50);
 
-	my @prefixes = qw(USII LS);
+	my @protos = map {$protos_avail[int(rand(@protos_avail))]} (0,0);
+	my @prefixes = qw(US LS);
+	$prefixes[0] .= join('', (map {$_->{code}} @protos));
 	my (@fds,@ports,@ips,@tags,@outputs);
-	for my $i (0,1) {
-		socket($fds[$i], AF_INET, SOCK_DGRAM, 0) or die $!;
+	for my $ix ([0,1],[1,0]) {
+		my ($i,$j) = @$ix;
+		my ($pr,$pr_o) = @protos[@$ix];
+		socket($fds[$i], $$pr{family}, SOCK_DGRAM, 0) or die $!;
 		while (1) {
 			my $port = rand(0x7000) << 1 + 1024;
-			bind($fds[$i], sockaddr_in($port, inet_aton($IP))) and last;
+			bind($fds[$i], $$pr{sockaddr}($port, inet_pton($$pr{family}, $$pr{address}))) and last;
 		}
 		my $addr = getsockname($fds[$i]);
-		($ports[$i]) = sockaddr_in($addr);
-		$ips[$i] = $IP;
+		my $ip;
+		($ports[$i], $ip) = $$pr{sockaddr}($addr);
+		$ips[$i] = inet_ntop($$pr{family}, $ip);
 		$tags[$i] = rand_str(15);
 		my $tagstr = ($i == 1 ? "$tags[0];1 " : '') . "$tags[$i];1";
 		my $o = msg("$prefixes[$i] $callid $ips[$i] $ports[$i] $tagstr");
-		$o =~ /^(\d+) ([\d.]+) 4[\r\n]*$/s or die $o;
+		$o =~ /^(\d+) ([\d.a-f:]+) ([46])[\r\n]*$/is or die $o;
 		$1 == 0 and die "mediaproxy ran out of ports";
+		$3 ne $$pr_o{reply} and die "incorrect address family reply code";
 		$outputs[$i] = [$1,$2];
 	}
 
-	push(@calls, [\(@fds,@ports,@ips,@tags,@outputs), $callid]);
+	push(@calls, [\(@fds,@ports,@ips,@tags,@outputs), $callid, \@protos]);
 }
 
-for (1 .. 30) {
+my $end = time() + $RUNTIME;
+while (time() < $end) {
 	sleep(1);
 	do_rtp();
 }