if your dad seldom talk on the phone then prepaid is the best way to go. And the cheapest around town is XoX. I have ported over to XoX and find it to be sufficient. It uses Celcom network which is good enough for me.

There are a bit of learning curve with it's DA/MA system but adiwarna's support is great. He replied all my PMs quickly and accurately.

So now, I do not need to topup my phone for 28 months if there are enough credits in it.