[Guide] Buying Taiwan Mobile 台灣大哥大 Pre-Paid SIM Card With Data
My Chunghwa Telecom prepaid sim worked great without configuration required.
Data packages I was offered were (unlimited usage).
1D $100
3D $250
7D $450
Had to call customer service to activate it. I speak Mandarin, not sure how well it would have gone in English.
With free wifi provided by the city and at airport and hotel, I am not sure an unlimited plan is required. I did do some metered usage and it looks like about NT $20 per MB, so if you plan to use a lot, unlimited is an easy choice.
The HSDPA speed is quite decent (several hundred Kbps). I am getting less than 100 Kbps in BKK.