Code Alarm was an early leader both in selling aftermarket car alarm systems and in supplying keyless entry systems to vehicle manufacturers for use in option packages or as dealer-installed systems. A while back, Audiovox bought Code Alarm. Since then, Audiovox has both preserved the Code Alarm brand and been fairly good about maintaining supply of replacement remote controls for older Code Alarm systems. (More recently, though, Audiovox has discontinued supply of several older Code Alarm keyfobs for systems that still have a fairly large installed base.)
There are always contrasting incentives for aftermarket alarm system manufacturers. On the one hand, alarm system manufacturers such as Audiovox do recognize that they have some obligation to support their existing customers by providing replacement keyfobs. Self-interest plays a role because they want to maintain goodwill with these customers. On the other hand, they and their network of dealers really want to sell you a new system rather than sell replacement remote controls to preserve the life of an older installed system. All in all, Audiovox puts much greater effort into developing new systems than into supporting older ones. No surprise there.
The good news for consumers is that Audiovox has reused the same basic transmitter technology in newer systems even as it has changed features and case designs. So, even if your model of Audiovox or Code Alarm system is no longer supported, it is likely that there is a replacement remote control available that will work with your system. For instance, Remotes Unlimited sells one replacement remote that works for over 40 different Audiovox and Code Alarm systems. Those include aftermarket alarm systems carrying the Audiovox, Pursuit, Prestige and Crimeguard brands. Interestingly, at least 12 different FCC IDs appeared on the original remotes for these systems, even though they are functionally the same.