I believe the best way to clean Bakelite and plastic Telephones is as follows:
Carefully dismantle the Bakelite telephones as much as possible. Then
Clean the Bakelite with a good non abrasive chrome cleaner such as autochrome.
Working the cleaner into the telephone in a circular motion.
The next stage and most important stage is to use "paste polishing number 5" from greygate chemical products specifically designed for cleaning Bakelite telephones.
Finally finish with a good quality "carnauda" car wax (that containing no silicones)
At each stage use plenty of elbow grease and patience. For the final polish use a clean cotton duster.