There are numerous reasons as to why a tracker might not have sent a signal that then resulted in no call or a late call, it would not be a good idea for me to give a full rundown on an open forum as to exactly what these reasons could be but I will say that in no way is the system designed to fail and there are thousands upon thousands of trackers that have been in vehicles for 20+ years and are still going strong, also the firm you refer to Parksy who monitors the alerts is Tracker themselves if it is actually a Tracker as opposed to being a tracking system, with a Tracker the company actually wants them to work, one of the biggest selling points is the success rate of what's fitted, in the case of a Tracker the success rate is measured by the recovery rate of vehicles fitted with trackers that are stolen, there is never going to be a 100% recovery but it usually hovers around the mid 90% mark, so if kits were designed to fail the recovery rate would be meaningless, also another thing that sets Tracker apart is the fact that in the event of a vehicle being stolen the people that do the tracking to find it is the police, not a single other tracking system is operated by the police but are monitored by sub contract companies, the systems available are monitored regularly by police forces with regualar reviews as whether or not to continue to use Tracker, to quote a line from as well known TV advert tracker does exactly what it says on the tin, nothing fancy but if your vehicle is nicked by some low life you've a better than 90% chance of getting it back, as to whether you want it that's another topic entirely.
BP