AC790S and AT entercnd password

You can connect to your AC790 at port 5510 over telnet to gain access to "AT shell" which responds to various AT commands, e.g. status or band selection. The same e.g. with AC810S. More advanced commands require entering password first, kinda to unlock them. It is "grouse" for AC810s. Does anybody know the password for AC790s? It is neither "grouse" or "whistler" I even tried few other, nothing is working.

 

Model: AC790S-1SPSUS