sorry for asking this question here, but i have searching around and could not find any more suitable topic to ask this question.

My iphone 3GS is updated previously by someone else to iOS 5.0.1
but now i realized that my iphone is actually an unlock set.
what is the limitation of an iphone unlock set?
is that means i cannot upgrade my firmware?

its Ok,
i get it.
unlock set means SimFree
sorry for asking noob question

is there any way to differentiate which is locked set, which is unlock?
bcoz i afraid if user bought a secondhand iphone, they will get conned.
some of the seller claim their phone is official unlock but it is actually jailbreak unlock.

the tips is mentioning about iphone 3G. not 3GS.

its good.
since previous iphone plan is rm68 with 800MB data only.
this one is cheaper.
but u got no free call and free sms.

But not everybody use apps to communicate
Some area dont have internet coverage and not all grandparents know how to use smartphone.

not really
senior citizen that use smartphone -> rare cases
senior citizen that dont know what is smartphone -> majority

not all area that have line have internet connection
some have 3g, some have edge, and some have none
if u put in edge, even sms thru whatsapp can delay more than 1 hour