What is your network’s cellphone now ? If you pay much for your mobile its time to turn to O2. As far as I know, one of the cheapest network with 2000 minute non peak time is O2.
If you click on e2save.com, you will find very cheap one year contract with latest phone model. Ooops, I am not their market person.
But anyway, this one best suggestionfor you, if you still shopping around.
Why then calling to Indonesia cheaper? With O2, 400 hundreds minutes a month, I spend about £ 11 with redemption scheme. You can use it in UK and you dial. Use your 400 minutes without paying anything.