The snom-events.xml is not related to polling the SNOM phone testing if the SNMP Agent on the phone is available. Can you make a
snmpget -v 1 -c <your-community-here> 192.168.100.40
from your OpenNMS servers CLI? Do you have configured the SNMP v1 community in the OpenNMS Admin section in "Configure SNMP Community Names by IP Address"?