We have a fairly big IT installation and our IT staff needs to be reachable 24/7. At the moment we have the following setup for "emergency" calls to our IT staff on our main Asterisk box:

• An incoming emergency number (connected via SIP trunk and a BRI card in case the SIP trunk goes down).
• When the number is called during the office hours, all the SIP phones of the IT staff are called simultaneously.
• When the number is called out of office hours interface, a list of mobile phone numbers is called, one after another until someone picks up.
• The list can be changed by the IT staff via command line script.

The setup works well, but the Asterisk is heavily used in a call center, has experienced some outages and misconfigurations, each of them bringing down the IT emergency number. So we'd like to put the IT emergency call functionality on a separate device. This does not need to be a big server, it even does not need to be Asterisk, it only has one purpose and should do it reliably. It should be very low-maintenance. Any suggestions for hard- and software?