Check with your provisioner for "far end disconnect" supervision, if they don't or won't provide it, check your
busycount=(somewhere between carelessness and caution)
settings in chan_dahdi.conf
If they do provide it set those settings (battery reversal, wink, whatever) to coincide in the same file, do NOT set the busycount under these circumstances or the phone call will hangup whenever the fork-lift drives past.
(many other posts in these fora, for clarification and if and when and what is needed just search for busydetect )
Indeed it does, but just for giggles make a call and have some one stand behind you a blow a whistle three times to see what I mean, it is always better to properly set up your analog/TDM trunks before you use them, If far end disconnect is available use it, this solution is a just a last ditch hack to detect the end of a call and relies on the "howler" sent by the telcos for the last 60 years after they replaced the operators, to remind subscribers to hang up the phone , it can take up to a minute to be sent, so it is usually better to use the default 8, as that is usually only a couple of seconds longer and seriously reduces spurious hangups, Far End Disconnect or CDC or whatever the local term is much quicker, but locale specific, (if available in your locale insist on it from the provider and use it)
I always try for the most efficient solution, rather than the easiest to accomplish. The increased customer satisfaction is ultimately worth it.