Intercom to control an inner door and and an outside door on same handsets

[martinxxxxxx]

I have an application where there is a block of flats with four flats which has an intercom system. There is an alleyway leading to the flats where there is another door. At the moment the people get through the other door by knowing a key code what I want to do is to use the intercom so that the flats can speak to the people at the first door and decide let them in the using the same handsets using the exsisting door entry system for the inner door. Is it possible to add a second call station to release outer door and to piggy back onto the existing system ?

 

[Taylortwocities]

Most door entry handsets only have a single door release button. Twin ones are around but really only practical for new installations as you'd need to change the handset in every flat, and an extra pair of wires is needed. Example

Room Master Handset With 2 Door Release Buttons.

12 - 24VDC

www.freewaysecurity.com.au

Cant see how you can "piggyback" on to the existing.

Not sure I understand the basis of your question though.
If a caller can get in through the existing door, once they have gained entry, why do they need to access the second door?

EDIT
Maybe you could also post your query on this other forum:

Alarms, CCTV & Telephones

Questions, comments and problems about alarms, security alarms, fire alarms, CCTV or telephones, telephone wiring, telephone extensions etc.

www.diynot.com

 

[oldbutnotdead]

First job is see if there are any spare cores running to the entryphones.
Second thing to think about is upgrading to a video system while you're at it (so if some chancer is prodding random buttons with a 'delivery' the occupants can have a look at them first)

 

[sparkymarka]

You need a 2 door switcher …..if it’s available for your system , if not then further information on the system make and model inc the handsets