Will it work if I take modem out? Didn't try to avoid alarm goes off

If ethernet disconnect it, if wifi change your password, if it's mobile then you will have to disable it in the installers menu as it will not like you taking the SIM card or aerial out live.

If any of these are enabled and you disconnect them it's likely to start beeping and reporting a path fault continuously. So not really advised anyway.

 

Really you should seek advise from ADT if your not happy with them get some other professional advise.

Bear in mind with it being an ADT system it's got custom firmware and radio frequency so anyone other than ADT would only give you limited support without replacing everything.

Ok, thank you everyone for all advises. 

5 hours ago, JohnJohnJohn said:

Ok, thank you for quick answer.

 

I have another question then:

Hi,

Can I arm/disarm this alarm from my mobile without adt subscription? It has mobile modem to report events.

You probably can 

 

It's unlikely locked tho your probably doing it wrong