How To: Solve "No Sim Card Installed" Error

Yesterday evening, I suddenly received the above error message. The SIM card was not detected by my iPhone.

Here's the method which I tried:-

1. Rebooting
2. Network Reset
3. Taking out and reinsert SIM
4. Clean the SIM Card
5. Tested on other phones such as Motorola, Dopod, iPhone 3GS, HTC, Nokia (only Dopod works whereas the rest doesn't)
6. Tested other SIMs on my iPhone 3GS and it works (it proves that the iPhone is working fine)

Finally, I get a SIM card replacement from Celcom (given FOC). 4 hours later, the phone was reactivated and working fine!