connector-telephony/asterisk_click2dial_event/registration_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
  Asterisk Click2dial CRM Claim module for OpenERP
  Copyright (C) 2013 Invitu <contact@invitu.com>
  The licence is in the file __openerp__.py

  Inherit event registration view to add 'Dial' button next to 'phone'
  field
-->

<openerp>
<data>

<record id="view_event_registration_form" model="ir.ui.view">
    <field name="name">asterisk.event.registration.form.dial</field>
    <field name="model">event.registration</field>
    <field name="inherit_id" ref="event_phone.view_event_registration_form"/>
    <field name="arch" type="xml">
        <field name="phone" position="replace">
            <group colspan="2" col="3">
                <field name="phone" widget="phone" colspan="2" />
                <button name="action_dial" context="{'field2dial': 'phone'}" string="Dial" type="object" attrs="{'invisible':[('phone','=',False)]}"/>
            </group>
        </field>
    </field>
</record>

<record id="view_event_form" model="ir.ui.view">
    <field name="name">asterisk.event.form.registration.tree.dial</field>
    <field name="model">event.event</field>
    <field name="inherit_id" ref="event_phone.view_event_form"/>
    <field name="arch" type="xml">
        <xpath expr="//field[@name='registration_ids']/tree/field[@name='phone']" position="replace">
            <field name="phone" colspan="2" />
            <button name="action_dial" context="{'field2dial': 'phone'}" string="Dial" type="object" icon="terp-call-start" attrs="{'invisible':[('phone','=',False)]}"/>
        </xpath>
        <xpath expr="//field[@name='registration_ids']/form//field[@name='phone']" position="replace">
            <group colspan="2" col="3">
                <field name="phone" widget="phone" colspan="2" />
                <button name="action_dial" context="{'field2dial': 'phone'}" string="Dial" type="object" attrs="{'invisible':[('phone','=',False)]}"/>
            </group>
        </xpath>
    </field>
</record>

</data>
</openerp>