code: public Lookup viewLookup(final BigInteger phoneNumber) throws UnauthorizedException, GeneralException, NotFoundException {
          if (phoneNumber == null) {
              throw new IllegalArgumentException("PhoneNumber must be specified.");
          }
          final Lookup lookup = new Lookup(phoneNumber);
          return this.viewLookup(lookup);
      }
docs: Send a Lookup request
  
  @param phoneNumber phone number is for viewing lookup
  @return Lookup
  @throws UnauthorizedException if client is unauthorized
  @throws GeneralException      general exception