Besides Monaco Telecom the French providers are availble. On this overview you see two poles, the thick pole is GSM. Two GSM900 and one GSM1800 are present. The orange building in front of the pole is not a house, here you can find the equipment.
<= A better overview of the site.
Below you can see a (quite large) microwave. Also on the picture on the left a (smaller) microwave is visible.
The building with the equipment. Monaco is hoping for more operators, at least there is some room for expansion ;-)