Don't worry about it until you get there, it's all really cheap. Expect
to pay about US$5 for a SIM card with a bit of credit on it. They are
available absolutely everywhere... though the one place in Malaysia
where it's hard to buy cell phone stuff is at the airport, for some
reason. There is a booth in the arrivals area, it's either Celcom or
Maxis. And there's a little-known convenience store on level 2 across
the car park bridge that has starter kits and reload cards (though
sometimes they're out of stock). Once you get on the train to KL Sentral
you'll face a wealth of options; at least 5 or 6 places on the main
level there selling SIM cards and reloads.

Far as I know it restarts the counter from when you reload. At least
that's how it seems to work with Digi.

miguel

I used MAXIS in my UK phone and did not find any coverage problems -
travelled around the Peninsula and Borneo (Sarawak).  MAXIS had one
other really good feature - it provided a special dialling code - 132,
I think - which enabled international calls to 20 countries inc US,
UK, Aus for 20 sen per minute - that was around 3 pence per minute.
From a mobile!  I could call home for less money than my family paid
to call a local taxi.  Truly, I was astonished.  I didn't use the
hotel phones at all, and it was much cheaper than UK folk calling me.
The MAXIS service is called 'Hotlink' - it has its own website.

Looking at the coverage maps, Celcom probably do have a bit better
coverage in the more rural parts of Borneo, if you are going to the
really rural bits.  If you're around most towns and on inter-town
roads even in Borneo, then either Maxis or Celcom would be fine, I'd
have thought.  If Celcom can match the 20 sen per minute for
international, then Celcom would definitely be the best choice.

I enjoyed my visits there - people were very friendly.  And the food's
great.

______________
best wishes,
Ron