because u sign up with singtel.
singtel say put these settings.
where did i find out? i used google, i go to singtel website, i
got the pdf file
Access point name (APN) identifies an IP
packet data network (PDN), that a mobile data user wants to
communicate with. In addition to identifying a PDN, an APN may also
be used to define the type of service, (eg connection to wireless application protocol
(WAP) server, multimedia messaging service
(MMS)), that is provided by the PDN. APN is used in 3GPP data
access networks, eg general packet radio service
(GPRS), evolved packet core (EPC).
u want to ask so much yet u dun use google or wiki. 