There were several types of microwave equipment. The main types were:
1. Michael - DMG 4,5 (one speech plus 3 teletype channels)
2. Rudolf -DMG 3aG (9 channels)
3. Stuttgart I and II - Fu G 03 (10 channels)
These types could be used together with carrier frequency equipment which allowed for several teletype links to be passed on each channel.
A good source on the German comm equipment is cdvant.org
The microwave equipment was used in all theaters. After the German forces in Stalingrad were surrounded it was this type of equipment that allowed for voice communications with the outside world.
The equipment used had a max range of 40km so in order to extend this to 110km it was necessary to find the highest possible location. The Germans built a tower on a hill near Nizhnyaya Chirskaya and during the night they raised the microwave tower and communicated with the encircled forces. During the day however they dismantled the tower because the Soviet airforce would destroy it.
This link was used by general Paulus to communicate with general von Manstein and other high level personnel.
Voice communications were not available after 22 December ’42 due to the withdrawal of the German front. [Source: FMS D-271 ‘The Battle of Stalingrad. Signal Communications in the Pocket of Stalingrad and Communications with the Outside’]
Other examples are available from FMS P-132 ‘Signal Communications in the East. By General der Nachrichtentruppen Albert Praun’, (available through fold3.com)