Error while displaying a collection of phones and emails from a contact

I want to display a list of contacts with phones and emails on an XHTML (JSF + PrimeFaces) page.

I can display everything I want in a test class:

package com.fercosmig.testes;

import java.util.List;

import javax.persistence.EntityManager;

import com.fercosmig.contato.model.Contato;
import com.fercosmig.contato.model.Email;
import com.fercosmig.contato.model.Telefone;
import com.fercosmig.contato.repository.ContatoRepository;
import com.fercosmig.util.jpa.JpaUtil;

public class TesteListaContatos {

    public static void main(String[] args) {

        EntityManager manager = JpaUtil.getEntityManager();

        ContatoRepository contatos = new ContatoRepository(manager);

        List<Contato> contatosLista = contatos.todos();

        for (Contato contato : contatosLista){
            System.out.print(contato.getId());
            System.out.print(" - ");
            System.out.print(contato.getNome());
            System.out.print(" - ");
            System.out.println(contato.getObservacao());

            for (Telefone telefone : contato.getTelefones()){
                System.out.print(telefone.getDdd());
                System.out.print(" - ");
                System.out.print(telefone.getNumero());
                System.out.print(" - ");
                System.out.print(telefone.getRamal());
                System.out.print(" - ");
                System.out.print(telefone.getTipo());
                System.out.print(" - ");
                System.out.println(telefone.getOperadora());
            }
            for (Email email : contato.getEmails()){
                System.out.print(email.getEmail());
                System.out.print(" - ");
                System.out.println(email.getTipo());
            }
        }
    }
}

The result of this test class in the console is:

1 - Alfredo Neves - colega da faculdade
11 - 955555555 - null - CELULAR - VIVO
11 - 12341234 - null - COMERCIAL - null
11 - 23452345 - null - RESIDENCIAL - null
[email protected] - PARTICULAR
2 - Rodolfo Complefica - colega de trabalho
11 - 956785678 - null - CELULAR - TIM
11 - 89078907 - null - RESIDENCIAL - null
[email protected] - PARTICULAR

I want to put this on the page

<h:form id="frm1">
    <h:dataTable value="#{consultaContatoBean.contatos}" var="contato"
        border="1" cellspacing="0" cellpadding="2">

        <h:column>
            <f:facet name="header">
                <h:outputText value="Id" />
            </f:facet>
            <h:outputText value="#{contato.id}" />
        </h:column>

        <h:column>
            <f:facet name="header">
                <h:outputText value="Nome" />
            </f:facet>
            <h:outputText value="#{contato.nome}" />
        </h:column>

        <h:column>
            <f:facet name="header">
                <h:outputText value="Observação" />
            </f:facet>
            <h:outputText value="#{contato.observacao}" />
        </h:column>

        <h:column>
            <f:facet name="header">
                <h:outputText value="Telefones" />
            </f:facet>
            <h:panelGroup>

                <ui:repeat var="telefone" value="#{contato.telefones}">
                    <h:outputText value="#{telefone}" />
                </ui:repeat>

            </h:panelGroup>

        </h:column>

        <h:column>
            <f:facet name="header">
                <h:outputText value="Emails" />
            </f:facet>
            <h:panelGroup>

                <ui:repeat var="email" value="#{contato.emails}">
                    <h:outputText value="#{email}" />
                </ui:repeat>

            </h:panelGroup>

        </h:column>

    </h:dataTable>
</h:form>

but displays the error below:

failed to lazily initialize a collection of role: com.fercosmig.contato.model.Contato.telefones, could not initialize proxy - no Session

The error is in the repeat structure that shows all phone numbers and all emails.

Does anyone have any ideas for solving this problem?