> > ATZ > > expect (OK) > > alarm > > AT > > expect (OK) > > alarm > > failed. > > > > Even if the modem doesn't hear the first "ATZ", it should hear the "AT", > > right? Given that it's been at least 5 seconds since the port was > > opened? It might have gotten confused by the first ATZ already. You need to wait before sending anything AFAIK. Michael