Here's a problem that existed prior to the year 2000 or thereabouts. It's since been fixed. If -clocal is set and there is no CD signal, then the "stty" command will hang and there is seemingly no way to set clocal to stop the hanging (except by running minicom). But minicom will restore -clocal when it exits. One way to get out of this is to use minicom to send the "AT&C" to the modem (to get the CD signal) and then exit minicom with no reset so that the CD signal always remains on. Then you may use stty again.