DefaultBinder in MVC problem

Question

Hi! I just started working in MVC and I have a problem:

public class ServicePhone
{
    public int AgreementId { get; set; }
    public List<PhoneNumber> Phones { get; set; }

    public ServicePhone()
    {
        Phones = new List<PhoneNumber>();
    }

    public PhoneNumber NewPhone { get; set; }
}

public class PhoneNumber
{
    public string Number { get; set; }
    public bool IsZoned { get; set; }
    public int ZoneOperatorId { get; set; }
    public string ZoneOperatorName { get; set; }
    public bool IsMultiChannel { get; set; }
    public int ChannelsNumber { get; set; }
    public bool IsPublic { get; set; }
    public bool ToDelete { get; set; }

    public bool IsValid()
    {
        return true;
    }
}

in page i write:

    <%for (int i = 0; i < Model.Phones.Count; i++)
     {%>
    <tr>
        <td>
            <%:Html.TextBoxFor(x => x.Phones[i].Number)%>
        </td>
        <td>
            <%:Html.CheckBoxFor(x=>x.Phones[i].IsZoned) %>
        </td>
        <td>
            <%:Html.TextBoxFor(x => x.Phones[i].ZoneOperatorName)%>
            <%:Html.HiddenFor(x=>x.Phones[i].ZoneOperatorId) %>
        </td>
        <td>
            <%:Html.CheckBoxFor(x=>x.Phones[i].IsMultiChannel) %>
        </td>
        <td>
            <%:Html.TextBoxFor(x => x.Phones[i].ChannelsNumber)%>
        </td>
        <td>
            <%:Html.CheckBoxFor(x=>x.Phones[i].IsPublic) %>
        </td>
        <td>
            <%:Html.CheckBoxFor(x=>x.Phones[i].ToDelete) %>
        </td>
    </tr>
    <%
    }%>

    <input type ="submit" id="addnumber" name="addnumber" value="+" />
    <input type ="submit" id="deletenumber" name="deletenumber" value="-" />

controller actions

    [System.Web.Mvc.OutputCache(NoStore = true, Duration = 0, VaryByParam = "*")]
    public ActionResult Create(int orderNumber)
    {
        var model = new ServicePhone();
        model.Phones.Add(new PhoneNumber
                            {
                                ChannelsNumber = 1, 
                                IsMultiChannel = true, 
                                IsPublic = true, 
                                IsZoned = false, 
                                Number = "skldfj", 
                                ZoneOperatorId = 10, 
                                ZoneOperatorName = "name"
                            });
        return View(model);
    }


    [HttpPost]
    [System.Web.Mvc.OutputCache(NoStore = true, Duration = 0, VaryByParam = "*")]
    public ActionResult Create(ServicePhone service, string create, int orderNumber, string addnumber, string deletenumber)
    {
        if (!string.IsNullOrEmpty(addnumber))
        {
            service.Phones.Add(service.NewPhone);
        }

        if (!string.IsNullOrEmpty(deletenumber))
        {
            service.Phones.RemoveAll(x=>x.ToDelete);// = service.Phones.Where(x=>!x.ToDelete).ToList());
        }

        return View(service);
    }

now problem: when i mark n phones to delete, in controller action items deleted successfully, but in returned view to browser with deleted last n items. I mark first 2 items, press button "-", in action deleted first 2 items, in view last 2 items dissapear, first 2 items marked. Why? Please, help me.