<prompt> Translate the following text to EnglishMoja ya sababu zilizotajwa kwa kupungua kwa kiasi cha barua za kibinafsi ni kushuka kwa viwango vya simu za umbali mrefu ambazo zimefanya mawasiliano ya simu kuwa ya bei nafuu zaidi na kuendeleza uingizwaji wa simu kwa barua za kibinafsi.  <response>: One of the factors cited for the decline in personal mail volume is falling long distance telephone rates which have made telephone communication more affordable and fostered substitution of telephone calls for personal mail. 