The only way to find out is by trial and error. It will not hurt a thing if the modem won't connect because the panel will simply hang up if the modem is incompatible.
As mentioned above you will need the correct installer code and password.
I've always felt the same as you about the inflated price for antiquated modems. I'm not sure why the manufacturers don't upgrade to new technology but I suppose it does provide a measure of security because not many hackers are going to be
War Dialing with a 1200 or 2400 baud modem.
If the system is going to be monitored I would bet the alarm company will program the system for you since they are going to have to program it to communicate with their receivers anyway.
