use warnings;
use strict;
use Data::Dump;
use XML::Rules ();

my $XML1 = '<root><phone><callTo>X</callTo></phone></root>';
my $XML2 = '<root><phone><callTo>Y</callTo>
	<callTo>Z</callTo></phone></root>';

my $parser = XML::Rules->new(
	stripspaces => 3|4,
	rules => [
		root => 'pass',
		phone => 'as is',
		callTo => 'content array',
		_default => sub { die "Unknown tag $_[0]" },
	] );
dd $parser->parse($XML1);
dd $parser->parse($XML2);

__END__

{ phone => { callTo => ["X"] } }
{ phone => { callTo => ["Y", "Z"] } }

##</code><code>##

use XML::Simple qw/:strict XMLin/;

dd XMLin($XML1, KeyAttr=>{}, ForceArray=>[]);
dd XMLin($XML2, KeyAttr=>{}, ForceArray=>[]);
dd XMLin($XML1, KeyAttr=>{}, ForceArray=>['callTo']);

__END__

{ phone => { callTo => "X" } }
{ phone => { callTo => ["Y", "Z"] } }
{ phone => { callTo => ["X"] } }

##</code><code>##

foo( "one" );
foo( ["two", "three"] );

sub foo {
	my $x = shift;
	# the following does the trick
	my @values = ref $x eq 'ARRAY' ? @{$x} : $x;
	for my $val (@values) {
		print "<$val>\n";
	}
}

__END__

<one>
<two>
<three>