You need BIS/BES no matter what OS you are on.

It'll still work as a regular phone though just no internet nor e-mail.

1) Check your phone is sim lock or not
Go to
Option -> Advance Optio--> sim cards
Type MEPD


If your Network is Active or Enable = LOCKED
If nextwork is Inactive or Disable mean your phone is unlocked and can use on Malaysia telco.

2) For 8900 model, it will work on all Malaysia telco. So no worry

3) If U have signed BIS package. To know if U have connection to BIS server. Your signal will show BIG CAPITAL LETTER example 3G, EDGE, GPRS

Smal letter like 3g, edge, gprs mean U are not yet connection to BIS or Your BIS is not active yet.