According to
this page, you will be able to use your
Skype credit to pay for wifi access with wifi networks around the world, including
True Corporation Public Company Limited. Other majors include
KSC,
Boingo,
Airborne Access,
Starhub,
Singtel and about 150 others. This is great news as the current state of pay for wifi is more of a game of account collection than anything else.
You will need
SkypeOut 
credit, and you pay per minute.
From 00.00 GMT on Saturday 20 March to 23.59 GMT on Sunday 21 March, Skype Access will be completely free to use from anywhere in the world.
How Skype Access works
Simply select an available public access WiFi network (the stronger the signal the better). Skype will automatically pop-up a message if you can connect to this network using your Skype Credit balance. If you don’t see a pop-up message, try another network.
Once you’re connected, you only pay per minute for what you use - no more paying for an hour’s access if you’re only online for 20 minutes.
More details