Pod ▁Touch , ▁and ▁Mac . ▁ ▁Until ▁the ▁release ▁of ▁iOS ▁ 6 , ▁Face Time ▁required ▁a ▁Wi Fi ▁connection ▁to ▁work . ▁From ▁iOS ▁ 6 ▁on wards , ▁Face Time ▁for ▁the ▁iPhone ▁and ▁i Pad ▁has ▁supported ▁Face Time ▁calls ▁over ▁cell ular ▁networks ▁( 3 G ▁or ▁L TE ) ▁provided ▁the ▁car rier ▁enabled ▁it , ▁which ▁by ▁mid - 2 0 1 3 ▁virt ually ▁all ▁carri ers ▁world wide ▁have ▁allowed . ▁Face Time ▁Audio ▁uses ▁about ▁three ▁meg aby tes ▁of ▁data ▁for ▁every ▁five ▁minutes ▁of ▁conversation , ▁with ▁Face Time ▁Video ▁using ▁significantly ▁more . ▁Cell ular ▁talk ▁time / min utes ▁are ▁not ▁used ▁after ▁switching ▁from ▁a ▁voice ▁call ▁to ▁a ▁Face Time ▁call . ▁ ▁Face Time ▁calls ▁can ▁be ▁placed ▁from ▁supported ▁devices ▁to ▁any ▁phone ▁number ▁or ▁email ▁address ▁that ▁is ▁registered ▁to ▁the ▁Face Time ▁service . ▁A ▁single ▁email ▁address ▁can ▁be ▁registered ▁to ▁multiple ▁devices ▁and ▁a ▁call ▁placed ▁to ▁that ▁address ▁rings ▁all ▁devices ▁simultaneously . ▁ ▁Stand ards ▁The ▁Face Time ▁protocol ▁is ▁based ▁on ▁numerous ▁open ▁industry ▁standards ▁although ▁it ▁is ▁not ▁inter oper able ▁with ▁other ▁vide ote le phony ▁systems : ▁▁ ▁H . 2 6 4 ▁and ▁A AC - ELD ▁– ▁video ▁and ▁audio ▁code cs ▁respectively . ▁ ▁S IP ▁– ▁I ET F ▁signal ing ▁protocol ▁for ▁Vo IP . ▁ ▁ST UN , ▁T URN ▁and ▁I CE ▁– ▁I ET F ▁techn