I have a facility with two Axxess nodes connected by IPRC. Node 1 has the T1/PRI card, node 2 accesses the PRI trunks through node 1.

When a 911 call is made from an extension on node 1, it displays the extension the call was made from on the admin DKS displays, and sounds an audio emergency tone on the same admin phones.

Node two doesn't work the same way; a 911 call made from a node 2 extension will show the emergency 911 call on a node 2 admin extenion, but will not sound an alarm tone. Is there any way to make node 2 function the same way as node 1?

Node 1 is software ver. 9.006, and node 2 is ver. 11.010

The audible alarm is not a native feature of the Axxess system. Is there a CTI application in use?

There is. Perhaps they are detecting this through the SMDR and triggering the alert tone back to the phone switch?

More likely via the OAI stream than SMDR.