[CollectionDataContract]
public class MyCustomerCollection : List<MyCustomer>
{
}
[DataContract]

public class MyCustomer
{
    private string _CustomerID;
    private string _CompanyName;
    private string _ContactName;
    private string _ContactTitle;
    private string _Address;
    private string _City;
    private string _Region;
    private string _PostalCode;
    private string _Country;
    private string _Phone;
    private string _Fax;

    public MyCustomer(string customerID, string companyName, string contactName, string contactTitle, string address, string city, string region, string postalCode, string country, string phone, string fax)
    {

        CustomerID = customerID;
        CompanyName = companyName;
        ContactName = contactName;
        ContactTitle = contactTitle;
        Address = address;
        City = city;
        Region = region;
        PostalCode = postalCode;
        Country = country;
        Phone = phone;
        Fax = fax;

    }
    public MyCustomer()
    { }

    [DataMember]
    public string CustomerID
    {
        get { return _CustomerID; }
        set { _CustomerID = value; }
    }
    [DataMember]
    public string CompanyName
    {
        get { return _CompanyName; }
        set { _CompanyName = value; }
    }
    [DataMember]
    public string ContactName
    {
        get { return _ContactName; }
        set { _ContactName = value; }
    }
    [DataMember]
    public string ContactTitle
    {
        get { return _ContactTitle; }
        set { _ContactTitle = value; }
    }
    [DataMember]
    public string Address
    {
        get { return _Address; }
        set { _Address = value; }
    }
    [DataMember]
    public string City
    {
        get { return _City; }
        set { _City = value; }
    }
    [DataMember]
    public string Region
    {
        get { return _Region; }
        set { _Region = value; }
    }
    [DataMember]
    public string PostalCode
    {
        get { return _PostalCode; }
        set { _PostalCode = value; }
    }
    [DataMember]
    public string Country
    {
        get { return _Country; }
        set { _Country = value; }
    }
    [DataMember]
    public string Phone
    {
        get { return _Phone; }
        set { _Phone = value; }
    }
    [DataMember]
    public string Fax
    {
        get { return _Fax; }
        set { _Fax = value; }
    }
}

    [ServiceContract]
    public interface IService
    {

        [OperationContract]
        MyCustomerCollection GetDataUsingLinq(string region);

    }