DSC Alarm and EnvisaLink or AlarmDecoer

I’m looking to install an alarm on my hose, and was looking at 2Gig, but the problem there is there is no option that I can find for local integration with HA. IT seems it MAY be possible through alarm.com, but that would require HA going out to the web and getting its info there - that requires internet connection. I want it to function even if there is no internet connection. I then looked at Elk, but that’s way over powered and over priced for what I’m looking for as I don’t need any of it’s add-on capabilities, like Automation.

Enter DSC - they’re reasonably priced, they have a serial interface (IT-100) and I found the EnvisaLink, which appears to give it 2Gig/Alarm.com type capabilities (alerts without all-out central station monitoring).

I found the info about AlarmDecoder, but does one need to use THEIR hardware to make it work? Or would theDSC IT-100 serial interface work just as well as their Serial interface?

I’ve read some posts about EnvisaLink working and being supported, however, it’s not listed on the ‘components’ page.

Since EnvisaLink seems to be an Alarm.com like service would HA be able to interface with it direct and function with or without an internet connection (and is it really fully supported, just forgotten about on the ‘components’ page)?

Any other thoughts?

I use a Honeywell Vista 20-P + alarm decoder. Cheap, easy to install, and very reliable. I had a Vista 20-P at my prev house + envisalink and I greatly prefer the no-cloud system that the alarm decoder uses. You do need to run a local web app to really have a remote access (I VPN to our network, then access the the alarm decoder web app to control it). Integrates easily with HA as well. If you decide to go that route, be sure to get a 6160RF keypad - it’s the same price as the regular keypad and adds in a wireless receiver.

The only real downside to the 20P panel is that it doesn’t report bypassed zones when armed. So if you have doors/windows open, bypass them, and arm the system, HA can’t tell when those sensors change status. However, I’m considering getting an SDR radio ($25) to read the sensors directly and integrate them into HA that way so at least the wireless would always report then.