xpresside,

found some info from this forum:
http://forums.macrumors.com/showthread.php?t=764706

from the forum, looks like the cause are push and notification. If you have these two things enabled, then your iPhone will be looking for connection when it needs to fetch data for push or notification service.

also from the forum, I find the tool "iPhone Configuration Utility 2.1" is a great tool to track what your phone is doing (console view). So far my phone is not connecting randomly or searching for updates "sesuka hati". I'll do some more tracking using this tool and I'll update if anything changes..

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Hmm my bill is not here yet, but according to the hotline my bill this month is about RM111 which I guess is normal considering the SMS i've sent etc .. no crazy data bill and I've loosened up this month

i juz got my iPhone last 2weeks...its on 22nd of OCT..but on 24th OCT, my bill reached RM176.95 deduct the RM40 advance payment, i have to pay RM136.95...i subscribed for the iValue 1...it should be RM60 but it double up. And now the bill reached me and it stated there  I had used up 65GB of network...what the hell?!! 2days can use up 65GB...Whats the matter? I complain to maxis CS and dont know what are they talking about what need 3days to activate my iValue la...But now the bill there stated everything is iValue1..the call and sms they deduct for my but not the network..The usage of my network is RM327.51..WHAT The hell wrong with their calculation? No tethering and sowhatever.

@`arthas,
I've 500MB p/month and thus far I haven't had problems with over usage.

@Cyan7,
The iValue plans should take effect about 2hrs after you get your phone; it'll take a while for Maxis to get it activated.

@Ken,
Wifi usage is not calculated in the Usage counter.

@Cyan7,
To be save, check with the person at the counter when you collect your phone

b4 digi subscriber,just because of iphone i have to convert maxis.The whole data usage issue is a big heartache. Thought of going back to Digi.Do not mind the penalty of 100+ plus the 300+subsidy paid to maxis. Guys,iphone 3gs on Digi works?

I took my phone on friday 8 pm last time and the staff told me my plan only activated on saturday 12 pm.

angemk, is it u use the data service before the plan was activated ? that time still count as pay per use charger

y took 2 days ? she just port in from other celco ?

mine took 14 hours like that ...

Having an iphone with no 3G or edge capability....hmm.....

oh Sh*t!
my phone showed tat my last month usage was 26mb ++
but yesterday when the bill come,it charged me 700mb++(currently idata 2)
how can it be a HUGE gap like this?
or anything wrong with the counter at maxis?
wat can i do?
maxis charger RM 400++
can i make a report or wat?

@12321,
I don't bother disabling APN since I've a data service plan; though I've done it before during the i3G days [that time, no data plan yet *grins*]. 

Will share this months' usage when I get it; bill cycle is 7th of the month.  I also did track for Jul & August but I didn't write that down.  If I'm not mistaken, Jul was like <25MB and August was <50MB

just gotten my first bill.. only 351 mb utilized nia... still got plenty to go for 1gb le..  so far no issue on the billing..

how do u guys maximize the data usage r ? dont know what to use anymore.. hehe

@Cyan7,
Yes that is absolutely right, and also beware of the 1st month bill due to Maxis pro-rating your entire plan.

@max2k,
You don't have to FULLY maximise it; don't be kiasu lah - but assuming there's something you aren't doing with ur iPhone because you were afraid of the data charges, U can now just go ahead and do that without worrying about your charges going way overboard; you should act check if the Usage counter correlates with your bill; that way there's still an indication for you to check

with all those push turn on also - my personal humble opinion 1GB also u cannot finish lor.. 
cause dont forget if you r on the go.. do u really surf that much ? battery will not last.. then u need to carry cable everywhere u go...

im currently didnt subscribe to any data plan.
im planning to subscribe iDATA plan which is the RM30 / 250MB per month.
so i want to ask, this idata plan need contract right?
but i cannot find how long we need to contract with them?

any of you guys know?
thanks for your kind help.