code: public byte[] sendBindResp(OutputStream os, int commandId,
              int sequenceNumber, String systemId, InterfaceVersion interfaceVersion) throws PDUStringException,
              IOException {
          
          OptionalParameter[] p;
          if(interfaceVersion != null) {
              OptionalParameter interfaceVersionParam = new OptionalParameter.Byte(Tag.SC_INTERFACE_VERSION, interfaceVersion.value());
              p = new OptionalParameter[] {interfaceVersionParam};
          } else {
              p = new OptionalParameter[] {};
          }
          
          byte[] b = pduComposer.bindResp(commandId, sequenceNumber, systemId, p);
          writeAndFlush(os, b);
          return b;
      }
docs: /*
  (non-Javadoc)
  
  @see org.jsmpp.PDUSender#sendBindResp(java.io.OutputStream, int, int,
  java.lang.String)