e.g. if you take iPhone4 16GB with Maxis iValue 1 (RM100) for 12-months, the phone costs RM1,590
You need to pay some downpayment, but to make it simple for calculation, let's just count 1590/12 mths = RM132.50 per month for the phone installment.

This means, every month, you need to pay RM132.50 (iPhone cost) + RM100 (Maxis plan)
= RM232.50 / mth (for 12 months)

Again, the above is not the exact calculation, but just to give an indication on the ownership cost for both device + plan.