Probably because it's pretty obvious it's a phone, since it has a distinguishable shape and all. As silhouettes used in these signs are rather simple, I would i

Probably because it's pretty obvious it's a phone, since it has a distinguishable shape and all. As silhouettes used in these signs are rather simple, I would imagine a "modern" phone would look like a million other things. Also, do you know how telegraphs look? Have you ever used one?