private void OnDeletePhone()
        {
            if (this.Entity.CustomerPhoneCollection != null &&
                this.Entity.CustomerPhoneCollection.Any(x => x.IsSelected))
            {
                var qureyItems = this.Entity.CustomerPhoneCollection.Where(x => x.IsSelected && (x.ID.HasValue && x.ID.Value > 0) && !x.IsDeleted).ToList();
                if (qureyItems.Any())
                {
                    CustomerAction.DeleteCustomerPhones(this.DBConnectionString, qureyItems);
                    qureyItems.ForEach(x => x.IsDeleted = true);
                }

                var items = this.Entity.CustomerPhoneCollection.Where(x => x.IsSelected && (!x.ID.HasValue || x.ID.Value <= 0)).ToList();

                if (items.Any())
                {
                    foreach (var customerPhone in items)
                    {
                        this.Entity.CustomerPhoneCollection.Remove(customerPhone);
                    }
                    var tempCollection = new CustomerPhoneCollection(this.Entity.CustomerPhoneCollection.ToList());
                    this.Entity.CustomerPhoneCollection = null;
                    this.Entity.CustomerPhoneCollection = tempCollection.InternalList;
                    this.Entity.NotifyPropertyChanged("CustomerPhoneCollection");
                }
            }
        }