I have never believed that the telcos in Singapore have 99% coverage because so far, I've never experienced such coverage since I moved to a 3G phone.
Personally, I do not care how the telcos measure their coverage because the 3G disconnect that I experienced on my phone is real. And don't give me the sales talk that it's because of many factors like my phone's components. I've tested it in an area where the 3G coverage is strong and I've encountered no such problems. The problem only comes when I'm moving around with a 3G connection.
This kind of problems will only occur if you do not have sufficient backend infrastructure to support the number of users logging into the 3G network at a given location. This has nothing to do with the phone's capability.
It's very easy to test out the 3G coverage. Enable your 3G network and disable automatic network connection. Just walk around see how many times your 3G network is disconnected. Then you will find that the telcos' claims of 99% 3G coverage is just a dream.