The entire electrical system in the old GDR was incorporated into the Western system, so maybe all the cables and pylons.
Yes, East Germany had the international code 37 which it gave up. That was then given to places such as Monaco, now 377 instead of the French 33.
It was. Points had been awarded for a long time before then, but it was not until 1975 that there was a jersey to show the leader.
I was trying to help cologne get away from the national grid and pylons towards phone lines. Unless you live in populated areas your telephone line is likely to be copper, and without them an international dialing code is redundant.