You should look into SNMP. I think of a single remote SNMP logging machine that generate reports and alert if the remote Elastix machine report errors or doesn't report at all. On Elastix machines you would create SNMP traps for everything you want to monitor.
I don't know how SNMP works fully, but I think you can get almost what you want to achieve with it. There may be some limitation that I don't know though.