Get a local SIM
If you are going to do anything in Singapore which requires you to be in contact with local people, then get a local SIM card for your mobile.
There are various "Pay As You Go" schemes, which can be activated immediately.
This applies to any country nowadays. No longer do you have to chuck money into the greedy mitts of you mobile 'phone company at home. I mean - US$2.50 per minute to 'phone home using a UK-SIM. I'd rather invest in 15,000km of string and a couple of cans. At least at the end of the call, I can fill the rest of my day untangling knots.