var users = (from u in db.Users
                         where ((soaStatus == 0) || (u.SOAStatusID == soaStatus))
                               && (string.IsNullOrEmpty(areaCode) || u.Phone1.Substring(0, 3) == areaCode)
                               && (string.IsNullOrEmpty(lastName) || u.LastName == lastName)
                               && (string.IsNullOrEmpty(state) || (u.State == state))
                         join uXt in db.User_x_Territories on u.Id equals uXt.UserID into sr
                         from x in sr.DefaultIfEmpty()
                         where (territoryID == 0 || x.TerritoryID == territoryID)
                         select u);