This configuration specifies how often to send a Confirmable (CON) message instead of a Non-Confirmable (NON) message, according to RFC 7641 section 4.5.
Leaving this configuration empty (0) sets it to a default of 24 hours.
Setting this to -1 will always use Confirmable notifications.
Note
using lwm2m_carrier.c this option can be set in kconfig by setting CONFIG_LWM2M_CARRIER_COAP_CON_INTERVAL.