I've enjoyed reading the discussions about midnight telco cutovers.
When I was working in the cable TV industry, we did midnight cutovers
too. But for a different reason: taxes.
When a cable TV company purchases another cable system, it usually
does not want to purchase an "operating entity" -- it wants to
purchase only the "assets" of the selling company. So to keep the tax
lawyers happy, the tech staff has to shut off all signals during the
In practice, it worked like this. I, representing the buyer, would
meet the seller's chief tech around 11:00 pm at the headend. We'd cut
off all signals at 11:59 pm, and turn them back on at 12:01 am.
During the two-minute break, we'd reprogram the character generators
(or connect new ones) so that the new company's name would be
displayed when the signals came back up. There were no signals at
midnight; ergo, for tax purposes, the business was not an operating
entity when the sale officially closed.
Of course, this was all a legal fiction: the lawyers certainly weren't
sitting around signing documents at midnight!
One of these purchases turned out to be very complicated: we were
buying a system that had seven headends interconnected by microwave.
But because a different combination of PEG access channels was
inserted locally at each headend, we had to shut down the signals at
each headend separately. And, of course, all seven shutdowns all had
to occur at precisely the same time.
This required seven two-man teams -- a total 14 technicians -- one
team at each headend. Each team consisted of one employee of the
seller and one employee of the buyer.
The lawyers insisted that we had to have a central coordination scheme
for this (we couldn't do it with something as simple as "synchronize
your watches"), so I set up a seven-way telephone conference call. We
even had a dress rehearsal the night before to make sure that all
seven teams would be able to get through all the locked doors and
fence gates required to reach their respective headends.
It all came off without a hitch, but the lawyers still weren't happy.
The following day, all 14 technicians (all of whom were now employees
of the buyer) had to come into the office and sign a pair of
affidavits (one for each company) affirming that they had, in fact,
done the job. Then each affidavit had to be notarized by two
notaries, one from the buyer and one from the seller.