Phone call came, claiming he is from singtel security department. Asked to check router and told me that there are a huge number of people using my internet connection.
when i asked for a local number to call back in case the line gets cut off, he was not able to provide. gave a 9 digit number. when i asked why, the caller got angry. first, claimed they are external vendor appointed by singtel, after that, claimed they are singtel when i asked for the vendor's company name.
also, they will transfer the line to another 'colleague' who will help to solve the issue. i asked for a number to call back again but was turned down. reason being, they have a huge flow of customers to assist, so if i call back, they can help me immediately. so i said to call back 30mins later.

I called singtel after that to verify and was informed, similar cases of scam.