Bulk insert on Contact Standard Object

Controller

public class BulkInsertController{
    public List<contact> contacts{get;set;}
    //Constructor
    public BulkInsertController(){
        initialize();
    }
    public void initialize(){
        contacts = new List<contact>();
        contacts.add(new contact());
       contacts.add(new contact());
      contacts.add(new contact());
    }
    public void save(){
        insert contacts;
    }
}

Page
<apex:page controller="BulkInsertController">
<apex:form>
    <apex:pageBlock title="Bulk Contact Insert">
        <apex:pageBlockTable value="{!contacts}" var="con">
            <apex:column headerValue="First Name">
                <apex:inputField value="{!con.firstname}"/>
            </apex:column>
            <apex:column headerValue="Last Name">
                <apex:inputField value="{!con.lastname}" required="false"/>
            </apex:column>
            <apex:column headerValue="Email">
                <apex:inputField value="{!con.email}"/>
            </apex:column>
            <apex:column headerValue="Phone">
                <apex:inputField value="{!con.phone}"/>
            </apex:column>
        </apex:pageBlockTable>
        <apex:commandButton action="{!save}" value="Save" immediate="true"/>
    </apex:pageBlock>
</apex:form>

</apex:page>