https://searchworks.stanford.edu/view/1460436
The first volume 1875-1925 is over 1000 pages. I'm telling you, Bell was an important organization with respect to modern sociology.
https://archive.org/details/bellsystem_HistoryOfEngineeringA...
Another interesting book is "Engineering and operations in the Bell System", which can be borrowed at archive.org:
https://archive.org/details/engineeringopera0000attb