"Single door wall cases"
(Click at the pictures to see a real version of the phone).

Picture 421, click for a real version, Museum für Post und Telekommunikation
 1889

Model M.89
Wall telephone, 1889
- case of walnut with one door
- 2 telephones model M.86
- carbon-cylinder microphone by
   Mix & Genest, Berlin
- induction coil
- battery calling
- DC ringer
- Lightning arrester
- local battery working with DC-
  busy test
1893

Model M.93
Wall telephone, 1893
- case of walnut
- 2 telephones model M.93
- carbon-cylinder microphone
- induction coil
- magneto calling M.92 / M.93
- DC ringer
- Lightning arrester
- local battery working with DC-
   busy test
Picture 422, click for a real version, private collection
Picture 423, Museum für Post und Telekommunikation
 1897

Model M.97
The 1893 type with another
microphone model "Carbon-Disc",
by R.Stock & Co., Berlin,
introduced in 1897
- magneto calling M.97
1898

Model M.98s (S&H)
Wall telephon, 1898
- case of walnut
- 1 tin telephone with ringmagnet
- carbon-bag microphone by
   Siemens & Halske
- induction coil
- magneto calling
- polarized ringer
- Lightning arrester
- local battery working with DC-
  busy test
Picture 424, no real version available
Picture 425, click for a real version, private collection
 1899/1900

Model M.99s/M.00s, 1899/1900
- case of walnut
- 1 telephone M.93 or telephone
   with ringmagnet M.00
- carbon-granule microphone
   (Vielhaben-Lewert)
- induction coil
- magneto calling M.98
- polarized ringer M.99
- Lightning arrester (only M.99s)
- local battery working with DC-
  busy test
1907

The M.00s Wall telephon since 1907
- case with desk top
- telephone M.93 or M.00
- carbon-granule microphone
   adjustable for high
Picture 426, no real version available
Picture 427
 Batterycase

All these telephones needed local
batteries for the microphone current
(2 cells) and, if no magnetos were
available, for calling the exchange
(6 cells).
These batteries were housed in little
wall cupboards.