Let's try the following:

1. Restart your device

2. Insert your SIM card into another device to ensure that the issue lies with the SIM card and not your device
 

Visit any Singtel Shop or self-help kiosks to replace your SIM card for FREE. If the SIM card is damaged, a replacement fee of $38.15 (includes GST) will apply.

Please bring along your original NRIC/FIN for verification.

Find a Singtel Shop