MS Dynamics CRM 2011 - Paging Retrieve Multiple Records

QueryExpression query = new QueryExpression(Contact.EntityLogicalName);
EntityCollection coll;
query.PageInfo.PageNumber = 1;
query.ColumnSet = new ColumnSet("firstname", "lastname");
do
{
    int RecordId = 1;
    coll = CRMServiceProxy.RetrieveMultiple(query);
    foreach (Entity e in coll.Entities)
    {
        Console.WriteLine(query.PageInfo.PageNumber + " - " + RecordId + " - " + e.Attributes["firstname"] + " - " + e.Attributes["lastname"]);
        RecordId++;
    }
    query.PageInfo.PageNumber++;
}
while (coll.MoreRecords);

public static OrganizationServiceProxy CRMServiceProxy
        {
            get
            {
                var uri = new Uri(System.Configuration.ConfigurationManager.AppSettings["CrmOrganizationUri"]);

                //Authenticate using credentials of the logged in user;      
                var cnt = new ClientCredentials();
                cnt.Windows.ClientCredential.Domain = System.Configuration.ConfigurationManager.AppSettings["CrmDomain"].ToString();
                cnt.Windows.ClientCredential.UserName = System.Configuration.ConfigurationManager.AppSettings["CrmUserName"].ToString();
                cnt.Windows.ClientCredential.Password = System.Configuration.ConfigurationManager.AppSettings["CrmPassword"].ToString();
                //cnts.Windows.ClientCredential = CredentialCache.DefaultNetworkCredentials;

                var sp = new OrganizationServiceProxy(uri, null, cnt, null);
                sp.EnableProxyTypes();

                return sp;
            }
        }