Thai regulator NBTC has given the nation's prepaid mobile customers until July 31 to register their numbers using identity verification before services will be suspended.
After the cut-off date, users of unregistered SIMs will be unable to make calls or use data services, the Nationreported.
As many as 90 million of the 100 million prepaid customers are using unregistered SIMs and could potentially be affected by the suspension, according to the report.
These users will need to register their SIMs by showing ID cards such as passports to their operators. Consumers will be able to register at retail chains and the branches of the nation's mobile operators.
Thai officials have been attempting to crack down on the use of unregistered SIMs since 2012. The latest government recently revived the issue by focusing on national security and fraud prevention arguments.
Unregistered SIMs will be able to receive calls after the cut-off date, and outbound calls and data use will be reactivated once a SIM is registered.
Pakistan's government has similarly set a deadline for SIM verification as part of the nation's adoption of its new Biometric Verification System (BVS). This edict was also motivated by national security concerns.