What is the purpose of the battery in the bell box?

[Gigagator]

Okay, the question in the title will be extremely obvious to many, and I understand that it's to provide a 'back up in the event of a power cut'.

However, in the event of a power cut, does the bell box siren and strobe not run from the 12v backup battery connected inside the panel in the house?

Long story short I have just about finished renovating a house that had an old Texecom Veritas R8 alarm which was fitted in 1996.
I have had to move the panel from a wardrobe to the attic, move the RKP to a different room, replace a couple of cable runs and I've also replaced all the PIRs (prev owner was a heavy smoker and the garage PIR had failed).

All is working lovely, it's all set up how we want it and everything is now shiny and clean, but the 12v battery had a date of 2004 on it, so was well past it (now replaced).
I would imagine the bell box battery would be of equal age or possibly older so I was just wondering what the exact purpose of the battery in there is if there is a backup battery in the alarm panel itself.

Many thanks in advance.

 

[bernardgreen]

If some criminal cuts the cable to the bell box then the battery in the box will enable the bell box siren to activate.

The cable will have a "hold off" wire which supplies 12 volt control signal to the bell box to prevent the bell box siren from sounding

 

[Wayners]

Cut or melt a hole in plastic bell box and cut siren wire.
Jobs a goodun.
If metal box fill with foam.
I wonder what companies do now to prevent this

 

[sparkymarka]

Ask ADT …They don’t have live bellboxes on most domestic systems …if I saw you 6m up a ladder at my house with a can of foam you wouldn’t be walking home …lol

 

[Gigagator]

If some criminal cuts the cable to the bell box then the battery in the box will enable the bell box siren to activate.

The cable will have a "hold off" wire which supplies 12 volt control signal to the bell box to prevent the bell box siren from sounding

Of course, that makes obvious sense now!