The best replacement for telegraph is telephone.

The best alternatives to telegraph are rated as following:
★★★★★  telephone
★★★  telegram
★★  guardian
★  telephone invented first
★  pony express
★  times
★  morse code

Your alternative for telegraph is not listed? Suggest!
Speaking about telegraph, one probably shouldn't forget about samuel morse.

Other search terms related to telegraph and their ratings are:
★★★★★ samuel morse
You have in mind a companion for telegraph and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of telegraph in all years. Click on graph for more.
telegraph
telephone
telegram