What are the requirements for registering a postpaid SIM card in Thailand without a work permit?

Many expats in Thailand have successfully registered postpaid SIM cards using just their passport, without the need for a work permit, contradicting some statements from service providers like True Move. Experiences shared by community members suggest that individual store policies may vary, and it is advisable to try different outlets or to speak to different staff members for assistance. Some have managed to obtain a postpaid SIM by providing additional documentation like a letter of residency or a Thai ID through a local contact. Additionally, many expats recommend exploring prepaid options due to fewer restrictions. It is also mentioned that some banks may tighten requirements for account holders, often demanding a work permit or other residency proof.