code: public boolean startCall(int channel, MuxInputStream in, MuxOutputStream out)
          throws IOException
      {
          // XXX: Eventually need to check to see if the channel is used.
          // It's not clear whether this should cause a wait or an exception.
  
          in.init(this, channel);
          out.init(this, channel);
  
          return true;
      }
docs: Starts a client call.