The policy file for the TCPIPT stack, /etc/TCPIPT.policy, contains a TTLSConfig statement pointing to the AT-TLS configuration file for that stack:
# This is a sample TCP/IP image configuration file # Path: /etc/TCPIPT.policy
# This is a sample TCP/IP image configuration file # applied to stack TCPIPT
LogLevel 15
TTLSConfig /etc/pagent_TTLS.conf3