Can you imagine not being able to call a German phone number from the US? AT&T's telephones still had to interoperate with (e.g.) the British Post Office's pho

Can you imagine not being able to call a German phone number from the US? AT&T's telephones still had to interoperate with (e.g.) the British Post Office's phones (and everybody else's) to remain relevant/useful. AT&T was very far from controlling all telephony equipment in the whole world.