NiteFinder: You can buy anywhere and everywhere, considering there is no registraiton, unlike Singapore - even their kidnappers/extortionist/rebels/terrorist use pre-paid to give radio interview and cannot be tracked .. and even their president get scam text, they cannot find culprit ... real use and throw people .. )
you can buy in Lucky Plaza, ask for Smart Roaming, and you can also, at P3 connection, (just on the upgoing escalater at 3rd floor, next to Dollar and Sense shop) in 3rd floor, ask for the load Pasaload, to load Philippine Number, where you can load it from Singapore, by texting a Singapore # with the pin. And can be used to load in Philippine also as they have a sms gateway to send load when you are in Philippine - so very useful.
Very useful, and also good to load up 'friends'

Though for friends, try to keep low denomination, like 100 peso. You can 'share load' upto 120 peso a day I think ...
Loads last for 30 day to 90 day, depending upon the value .. like 100 peso 10 day, 300 peso, 30 day, 500 peso 90 or so..
And, the sim expires if you don't load atleast once every 6 months I think ...
NinjaAssasin: you forgot to mention the part of free receiving of text, from Philippines number, when you are in Singapore,
PROVIDED, you enable roaming, by sending a stupid fxked text, (roam on) or else, the Sim cannot be remote activated ..
I sometimes forgot, so had to send the phone + sim back to philippines, for some friend to turn it on, send text to enable roaming, and then bring the phone back..
So much developed their mobile network is.
For online load, you can use pldt-online.com to load Smart (and also send gift voucher/roses .. to impress your loved ones

and to the ladies who stole you HEART

)
And the best online load is
www.pa-load.com
all reliable, but online load a bit expensive ..