code: public LookupHlr requestLookupHlr(final BigInteger phoneNumber, final String reference) throws UnauthorizedException, GeneralException {
          if (phoneNumber == null) {
              throw new IllegalArgumentException("Phonenumber must be specified.");
          }
          if (reference == null) {
              throw new IllegalArgumentException("Reference must be specified.");
          }
          final LookupHlr lookupHlr = new LookupHlr();
          lookupHlr.setPhoneNumber(phoneNumber);
          lookupHlr.setReference(reference);
          return this.requestLookupHlr(lookupHlr);
      }
docs: Request a Lookup HLR (lookup)
  
  @param phoneNumber phone number is for request hlr
  @param reference   reference for request hlr
  @return lookupHlr
  @throws UnauthorizedException if client is unauthorized
  @throws GeneralException      general exception