docs: public String getVariable(final Channel channel, final String variableName)
      {
          String value = "";
          final GetVarAction var = new GetVarAction(channel, variableName);
  
          try
          {
              PBX pbx = PBXFactory.getActivePBX();
              if (!pbx.waitForChannelToQuiescent(channel, 3000))
                  throw new PBXException("Channel: " + channel + " cannot be retrieved as it is still in transition.");
  
              ManagerResponse convertedResponse = sendAction(var, 500);
              if (convertedResponse != null)
              {
                  value = convertedResponse.getAttribute("value"); //$NON-NLS-1$
                  if (value == null)
                      value = "";
                  CoherentManagerConnection.logger.debug("getVarAction returned name:" + variableName + " value:" + value); //$NON-NLS-1$ //$NON-NLS-2$
              }
          }
          catch (final Exception e)
          {
              CoherentManagerConnection.logger.debug(e, e);
              CoherentManagerConnection.logger.error("getVariable: " + e); //$NON-NLS-1$
          }
          return value;
      }