বিশ্বের কোন দেশে সর্বপ্রথম টেলিযোগাযোগ নেটওয়ার্ক চালু হয় ?
In 1792, Claude Chappe, a French engineer, built the first fixed visual telegraphy system (or semaphore line) between Lille and Paris. However semaphore suffered from the need for skilled operators and expensive towers at intervals of ten to thirty kilometres (six to nineteen miles). As a result of competition from the electrical telegraph, the last commercial line was abandoned in 1880.
1792