This attribute specifies duration of the service lifetime supervisory
timer which applies to non call-associated sessions providing
bearer-independent connection-oriented transport for supplementary
services. The timer limits the duration of a virtual call. It is started
at the ingress Passport at the moment the first response message
from the destination PBX has been received and stopped when the
non call-associated session is released. If the timer expires, the non
call-associated session is cleared.
This timer is equivalent to the T-CCBS6 timer described in the
relevant supplementary service specifications.
A change of the timer value does not apply to timers already
running.