Session Initiation Protocol (SIP)
UDP and Linux tuning: https://www.ibm.com/support/knowledgecenter/SSAW57_8.5.5/com.ibm.websphere.nd.doc/ae/tsip_tunelinux.html
Consider JVM and thread pool tuning: https://www.ibm.com/support/knowledgecenter/SSAW57_8.5.5/com.ibm.websphere.nd.doc/ae/tsip_tune_ha.html