... . Features of stability, reliability, safety, and humanizing control enable it to be widely used for alert in shops, convenience stores, offices ... only be automatically assigned and users a bit more work to change4.More User-friendly. e.g. can use landline phone ... module, 10~20seconds record, voice alarm function10."Watch dog" function, to avoid system down.11.Backup DC 12V 7Ah Sealed lead ...