For starhub users, I have friend having such problems.
They miss out some SMS when we send to them.
Either from Singtel/M1 network.
I think the starhub sms server might be congested at times.
My cousin using starhub mobile complain that she cant make outgoing calls
near her school at Choa Chu Kang area during certain time eg. evening.
to solve this problem
all sign M1
no problem liow