I would like to upgrade it and use a cheap monitoring internet service. Won’t have a land line but wifi/Ethernet and also have a Nest Thermostat.
suretyDIY is a DIY Alarm.com services and monitoring provider. Systems run on a primary cellular connection, with options for broadband backup. They don’t require a landline.
Nest thermostat integration is an included option in Gold Interactive.
Any suggestion for a DIY install? What do I need to buy and how hard is it to setup in the existing framework
A 2GIG Go!Control or GC3 Panel is a good option, using the TAKE-345 to reuse existing hardwired sensor zones. Each TAKE-345 supports 8 hardwired zones.
The existing system would simply be used to power existing wired sensors that require it (motion detectors, glass break, etc.) as well as the TAKE-345. You would not reuse the old keypads.
You can typically reuse the keypad wiring to connect your control panel and the plug in power supply it comes with, if you want to install the new control panel in place of one of the keypads.