connector-telephony/event_phone/event_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Copyright (C) 2014 Alexis de Lattre <alexis@via.ecp.fr>
  The licence is in the file __openerp__.py
-->

<openerp>
<data>

<record id="view_event_registration_form" model="ir.ui.view">
    <field name="name">event_phone.event_registration.form</field>
    <field name="model">event.registration</field>
    <field name="inherit_id" ref="event.view_event_registration_form"/>
    <field name="arch" type="xml">
        <field name="phone" position="attributes">
            <attribute name="widget">phone</attribute>
        </field>
    </field>
</record>

<record id="view_event_form" model="ir.ui.view">
    <field name="name">event_phone.event.form</field>
    <field name="model">event.event</field>
    <field name="inherit_id" ref="event.view_event_form"/>
    <field name="arch" type="xml">
        <xpath expr="//field[@name='registration_ids']/form//field[@name='phone']" position="attributes">
            <attribute name="widget">phone</attribute>
        </xpath>
        <xpath expr="////field[@name='registration_ids']/tree/field[@name='phone']" position="attributes">
            <attribute name="widget">phone</attribute>
        </xpath>
    </field>
</record>


</data>
</openerp>