Part of the code is the system is required to be a permanent fixture of the home and must be maintained under a service contract etc.
If this is correct, I hope it applies only to systems where smokes are powered by, and monitored at, a central panel substituting for the usual 117VAC smokes with battery backup as usually found in residential construction. My Elk M1 system has no connection to the smokes and is primarily intended for intrusion detection. It is not monitored by a central station, and has no service contract. Since there is no code requirement for such a system in my area, I don't anticipate I'm guilty of any code violation.