code: @Override
      public void onUnstructuredSSRequest(UnstructuredSSRequest unstrReqInd) {
          if (logger.isDebugEnabled()) {
              logger.debug(String.format("Rx UnstructuredSSRequestIndication. USSD String=%s ", unstrReqInd.getUSSDString()));
          }
          MAPDialogSupplementary mapDialog = unstrReqInd.getMAPDialog();
  
          try {
              CBSDataCodingScheme ussdDataCodingScheme = new CBSDataCodingSchemeImpl(0x0f);
  
              USSDString ussdString = this.mapProvider.getMAPParameterFactory().createUSSDString("1", null, null);
  
              AddressString msisdn = this.mapProvider.getMAPParameterFactory()
                      .createAddressString(AddressNature.international_number, NumberingPlan.ISDN, "31628838002");
  
              mapDialog.addUnstructuredSSResponse(unstrReqInd.getInvokeId(), ussdDataCodingScheme, ussdString);
              mapDialog.send();
  
          } catch (MAPException e) {
              logger.error(
                      String.format("Error while sending UnstructuredSSResponse for Dialog=%d", mapDialog.getLocalDialogId()));
          }
      }
docs: /*
  (non-Javadoc)
  
  @see org.restcomm.protocols.ss7.map.api.service.supplementary. MAPServiceSupplementaryListener
  #onUnstructuredSSRequestIndication(org.mobicents .protocols.ss7.map.api.service
  .supplementary.UnstructuredSSRequestIndication)