It has been suggested that they (or some such) did.

If so, is there any supporting evidence?

I am mainly interested in the situation in Germany during the Thirties ...

Holland would be a bonus.

As would the likely start dates.

Are links to actual transcripts too much to hope for?

I know that the Gestapo used wire tapping (at least during the war)
because some years ago, I read a description of the techniques and
equipment used for those purposes. Among other things, most of which I
have forgotten, the use of wax records for recording tapped phone
calls was mentioned. Unfortunately, I can't remember at all what the
name of the book was.

As for transcripts: If those are still existing, they are available in
German archives as all Gestapo files. Due to the federal structure of
Germany, the surviving Gestapo records of all kinds are not stored in
one place. Instead, they are scattered all over the country in the
Bundesarchiv and various Staats- and Landesarchive. It is impossible
to say what is kept where. This official list of government archives
in Germany might help:
http://www.bundesarchiv.de/service/links/archive/00854/


Greetings,
Scriptor

Hi, Scriptor

We also know (from your previous work) that 'somebody' intercepted
trans-Atlantic phone calls ...

It's interesting that 'they' used wax records because I seem to recall
that the Germans had invented tape recording sometime before the war.
I read somewhere that they had shown it at a Radio Exhibition in
Berlin(?) but had then withdrawn it as a secret.

Many thanks for your comment.

All the Best

Bryan

Evidently, the Americans discovered it after the war and popularised it.

Indeed, magnetic tape recording was known. At the 12th Deutsche
Funkausstellung in Berlin, August 1935, AEG presented the magnetic
tape recording device "Magnetophon K 1". Following a concept developed
by Theo Volk, it used a 6.5 mm wide magnetic tape, running at a speed
of 1 m/s and capable of recording frequencies up to 6000 Hz. One
30-cm-reel had a recording capacity of 20 minutes.
On 19 November 1936, a concert of the London Philharmonics was
recorded on magnetic tape manufactured by BASF (the recording session
took place in the culture centre of BASF in Ludwigshafen, by the way).
This recording is still in good condition today.
Some time ago, when I did some private research on the history of
radio broadcasting in Germany, I found out that at least the
Reichssender Berlin owned and used some tape recording devices during
the war years. I wish I had made detailed notes of that.

Greetings,
Scriptor

Very many thanks for your further comment, Scriptor.

I am rather disappointed that fp-ga (Freddy) has not jumped in on this
... I hope he's alright ...

Hi, Bryan

I'm alright, thank you ...

Concerning the Netherlands I suppose the best place to ask would be
"Het Nederlands Instituut voor Oorlogsdocumentatie":
http://www.niod.nl/

"It is the centre in the Netherlands for information and research on
the Netherlands ... during the Second World War."

http://www.niod.nl/content/en/general.asp

"Gestapo-Dienststellen" in the Netherlands ("Gestapo siehe Sicherheitspolizei"):
http://www1.jur.uva.nl/junsv/NED/NL-Dienststelle.htm

"Wire tapping" not mentioned here:
"Organisationsstrukturen der deutschen Besatzungsverwaltungen in
Frankreich, Belgien und den Niederlanden unter besonderer
Berücksichtigung der Stellung des SS- und Polizeiapparates" (1997)
http://www.ub.uni-konstanz.de/v13/volltexte/1999/115//pdf/115_1.pdf

However, you are mainly interested in pre-war wire tapping?

I could not find a date when tapping started.

There are several books written by Heinz Boberach on the subject of Gestapo etc.
These books may have the information you are looking for.
Heinz Boberach:
http://www.bod.de/autoren/boberach_heinz.html

No date (1936, or later) "Telefonüberwachung":
http://www.bnbt.de/~tr1035/bt/wer/index.htm  then click on "Reissinger, Hans"

Bryan, does your question only refer to the Gestapo? 

Or are you also interested in links mentioning the tapping by the
"Forschungsamt" (Göring)?

"Forschungsamt" as in 
http://answers.google.com/answers/threadview?id=339504
and
http://answers.google.com/answers/threadview?id=57708

Hi, Freddy

Very many thanks for the various links, as usual all are very relevant
and exciting ...

All the Very Best

Bryan