Looking for suggestions. Customer would like to use his system for emergency evacuation notification if possible. First building would be ok as I could tie an analog extension into their paging amplifier night ringing input. Second building is the issue. There is no copper connection from the 9100 and they are already using the speaker leads off an IP set in the phone room into that amplifier for paging and night ringing so they would no doubt confuse an emergency signal for ringing.

Also concerned that if someone from the second building is in the main building, they wouldn't associate the "night ringer" with an emergency.

Thinking of using two IP phones in a separate department group, change the ring tone on them and connect to the amplifiers music inputs. At least that way they would sound the same in each building.

Any other ideas or recommendations?

What about a SIP license and an ATA?

But I do like you Two phone idea as they would sound the same.