5 ▁he ▁attended ▁several ▁post grad uate ▁courses ▁at ▁ren owned ▁univers ities ▁in ▁Vienna , ▁Mun ich ▁and ▁Gött ingen , ▁where ▁he ▁met ▁many ▁of ▁the ▁leading ▁scientific ▁personal ities ▁of ▁the ▁time , ▁such ▁as ▁David ▁Hil bert , ▁Hermann ▁M ink owski , ▁Felix ▁Klein , ▁Carl ▁David ▁Tol mé ▁Run ge , ▁Edu ard ▁R ie cke , ▁Ludwig ▁Pr and tl , ▁Emil ▁Wie ch ert ▁and ▁the ▁younger ▁phys ic ists ▁such ▁as ▁Max ▁Born , ▁Max ▁von ▁La ue ▁and ▁Peter ▁Deb ye . ▁ ▁Multiple ▁Tele phony ▁In ▁November ▁ 1 9 0 5 , ▁Ma ior ▁was ▁employed ▁as ▁an ▁engineer ▁in ▁the ▁Electric ity ▁Labor atory ▁of ▁the ▁General ▁Director ate ▁of ▁Post s ▁in ▁Budapest . ▁In ▁ 1 9 0 6 ▁he ▁managed ▁to ▁transmit ▁five ▁calls ▁simultaneously ▁on ▁a ▁single ▁ 1 5 - km ▁tele phone ▁line , ▁without ▁inter ference ▁between ▁them . ▁His ▁" The oret ical ▁Found ations ▁of ▁Multiple ▁Tele phony " ▁was ▁published ▁in ▁ 1 9 0 7 ▁in ▁the ▁" E le kt rote chn ische ▁Zeitschrift " ▁and ▁then , ▁in ▁ 1 9 1 4 , ▁" The ▁Use ▁of ▁High - Fre quency ▁Altern ating ▁C urr ents ▁in ▁Te legraph y , ▁Tele phony ▁and ▁for ▁Power ▁Trans mission " ▁was ▁published ▁in ▁" The ▁Electric ian ." ▁ ▁Return ▁to ▁Roman ia ▁After ▁World ▁War ▁I ▁and ▁the ▁union ▁of ▁Trans ylvan ia ▁with ▁Roman ia