All sorts of advertising material has been produced to promote various manufacturers products and also innovative use of the telephone.

From the 1930's/40's these images show ink blotters with telephone industry promotions

All sorts of interesting telephone "add-ons" were produced as advertising give-aways to promote local area businesses. These "give-aways" are now in great demand by collectors and their value has increased substantially. 

And naturally the local area businesses used all sorts of magazine and newspaper advertising to promote their products etc. - for any-one interested in this type of material, there are thousands of items listed for sale on the Internet.

And of course, the Telephone industry itself used a lot of magazine advertising to promote their own products and services - how else would we know just how good they are?