MI2A Country's Network Issue

Nov 20, 2013
Hi, i'm using Mi2A, still on MIUI-3.10.18, didn't have time to update yet.

My current location is in Jakarta, Indonesia, and i have Postpaid Telkomsel (Kartu Halo) as my provider.

Last week, i went to Singapore, and i couldn't connect to every networks there. Telkomsel has Singtel as their partner, but i couldn't event click on Singtel button to connect (grey and unclickable). I tried automatic search and manual search, found another 2 networks (forgot their names) but couldn't connect.

My questions are :

1. Is this ROM issue or something else?
2. Is this happened because i haven't update my ROM?
3. I want to know Singapore's Mi2A owners experience, because i have to go to Singapore frequently.