We use Cisco's ATA 186 to drive two external ringer bells at the vehicle maintenance garage at a local school district, because the Cisco IP Phones in the office don't ring loud enough to be heard over the shop noises.
The ATA 186 has two FXS phone ports, and gets its power from an external power pack/transformer. You can plug a regular analog telephone or fax machine into them, but we have a distinctive external ringer plugged into each. Each port is then configured to share a line number with one of the two lines on the 7940 in the garage office. When you call one of the numbers, both the IP Phone and the external ringer ring (but only the IP Phone can be answered).
I don't know who manufactured this unit, it was in place long before we installed the IP Telephony system. But if you use an Internet search engine and input the terms "external ringer" and "loud" you should get some useful leads.
I think the only parameter you need to be aware of is the voltage or current needed to operate the external ringer: the ATA 186 is not very powerful, there may be ringers which need more than the ATA 186 delivers from its FXS ports. Not knowing whether our bells would work (since we had no documentation), we took a chance and connected them anyway since the ATA 186 is a relatively inexpensive piece of hardware. It works great.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.