code: protected void decodeMandatoryVariableBody(ISUPParameterFactory parameterFactory, byte[] parameterBody, int parameterIndex)
              throws ParameterException {
          switch (parameterIndex) {
              case _INDEX_V_SubsequentNumber:
                  SubsequentNumber subsequentNumber = parameterFactory.createSubsequentNumber();
                  ((AbstractISUPParameter) subsequentNumber).decode(parameterBody);
                  this.setSubsequentNumber(subsequentNumber);
                  break;
              default:
                  throw new ParameterException("Unrecognized parameter index for mandatory variable part: " + parameterIndex);
          }
      }
docs: /*
  (non-Javadoc)
  
  @see org.restcomm.protocols.ss7.isup.ISUPMessageImpl#decodeMandatoryVariableBody (byte[], int)