These wierd letters are the letters that were used on Austrian phone dials from 1927 until the early 1960ies.
Letters were:
1 I
2 F
3 A
4 B
5 R
6 U
7 M
8 L
9 Y
0 Z
Read backwards you get the nickname of these old phones - ZYLMURBAFI. Subscriber numbers were 1 letter, 5 numbers, e.g. A 25 387. In my area the changeover occurred in 1961, in 1962 the numbers were changed again (from letters to 32 xx xx, then to 34 xx xx and 34 xx xxx)
I've never seen a real ZYLMURBAFI, it seems that the dials were all changed. Today there are only very few rotary phones in service, the post office took them back during the changeover to digital switching, only by special request you could keep them, many people were even made believe that rotary phones don't work any more.
