<?xml version="1.0" encoding="UTF-8"?>

<phone>
<number>123</number>
<number>1523</number>
</phone>

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">

<xs:element name="phone">
<xs:complexType>
<xs:element name="number" type="xs:string" lenght="3"/>
</xs:complexType>
</xs:element>

</xs:schema>