AT&T Security Systems Frequently Asked Questions

What is the CRC Code For?
The CRC, or cyclical redundancy check, is in place to keep programmers from making typographical errors when activating a communicator. Learn more here!

Can I Change the Rev Chip on a Vista 21iP?
While you can upgrade the prom chip in a Vista-21iP, it may not always be advantageous to do so. Find out when you should, or shouldn’t upgrade the chip.

How Do I Enable the GSMVLP4G on my Honeywell L3000?
Once the GSMVLP4G has been physically installed, you must enable it in programming. Learn how to enable cellular alarm communication on the LynxPlus.