Cellular Back Up units a classic example why you need to hook them direct and not use Dial Capture

Uplink unit utilizing a Line capture card

When it comes to connecting a  3rd party cellular back up unit to a Burglar alarm system like a Uplink unit  It can be done in 2 ways . Direct wired to  panels bell output or thru a technology known as Dial capture.

The draw back to direct attachment is some 3rd party  cell communicators then only send a general burglar or fire signal and individual  zone codes are not sent.  Where as if you use  Dial capture it can send full data from the panel.
Which can be useful when you have a large complex to know exactly what is going on. The problem as one of my clients found out the other day is when you use Dial Capture it may not always trip the cellular unit and send a message when there is an alarm.

The problem my customer a very large food distributor who is adding on a new warehouse section and updating there old section  which I am in the process of installing  a new system and merging his old systems into  the new systems  ran into was when a door set for 24 hour alarm was opened it should have contacted the central station it did not. Unlike if the Uplink communicator was direct tied and a signal would have been sent his original installer installed an Uplink unit with a Dial capture card made by the now closed  Stealth Laboratories.
 The  Dial Capture unit measures voltage and line amperage and when it does not see it takes over the phone line and sends the signal . But the problem is the phone line was not dead it still had voltage and was dialing  but when it made contact the central receiver could not hear the tones. I confirmed this after they got a failure to Communicate trouble at the panels keypad and took a butt set and tried dialing out .
This has always been a problem for  all  Burglar and Fire Alarm System phone line monitors. They only can tell if line has voltage and amperage not if the phone line is actually operable.

Had in this case the Uplink unit been direct wired to the bell output of the panel  the  message would have went out  to central and then a fail to communicate message would have still showed up at keypad that would have required further investigation but at least the message would have gotten out instead it did not.  Luckily the plant was open for business and it was an accidental door opening by a construction person but what if it had been a burglar when they where closed the message never would have gotten out . Needless to say the new system is not designed this way instead I am using the manufacturers  cellular with  internet back up unit which attaches directly to the panel and not using line capture.
To prevent this type of issue from happening.
needless to say this is something which when installing a cell back up unit you must take into consideration and if possible if using line capture also connect the cell unit directly if possible.