0 s . ▁In ▁the ▁early ▁days ▁of ▁cell ular ▁hand sets , ▁phone ▁functionality ▁was ▁limited ▁to ▁d ial ing , ▁and ▁voice ▁input / output . ▁ ▁When ▁the ▁second ▁generation ▁of ▁mobile ▁tele com s ▁( so - called ▁ 2 G ) ▁was ▁introduced ▁in ▁Finland ▁by ▁Rad i olin ja ▁( now ▁El isa ) ▁on ▁the ▁G SM ▁standard ▁( now ▁the ▁world ' s ▁most ▁common ▁mobile ▁technology ▁with ▁over ▁ 2 ▁billion ▁users ) ▁in ▁ 1 9 9 1 , ▁the ▁digital ▁technology ▁introduced ▁data ▁services . ▁S MS ▁text ▁mess aging ▁was ▁the ▁first ▁such ▁service . ▁The ▁first ▁person - to - person ▁S MS ▁text ▁message ▁was ▁sent ▁in ▁Finland ▁in ▁December ▁ 1 9 9 4 . ▁S MS ▁( Short ▁Message ▁Service ) ▁gradually ▁began ▁to ▁grow , ▁becoming ▁the ▁largest ▁data ▁service ▁by ▁number ▁of ▁users ▁in ▁the ▁world , ▁currently ▁with ▁ 7 4 % ▁of ▁all ▁mobile ▁subscri bers ▁or ▁ 2 . 4 ▁billion ▁people ▁active ▁users ▁of ▁S MS ▁in ▁ 2 0 0 7 . ▁ ▁One ▁advantage ▁of ▁S MS ▁is ▁that ▁while ▁even ▁in ▁conference , ▁users ▁are ▁able ▁to ▁send ▁and ▁receive ▁brief ▁messages ▁un ob tr us ively , ▁while ▁enjo ying ▁priv acy . ▁Even ▁in ▁such ▁environments ▁as ▁in ▁a ▁restaurant , ▁c afé , ▁bank , ▁travel ▁ag ency ▁office , ▁and ▁so ▁on , ▁the ▁users ▁can ▁enjoy ▁some ▁priv acy ▁by ▁sending / rece