Excuse me for being the noob falang on this subject, but I have noticed a lot of private vendors at night markets who sling prepaid sim cards and top up from a table.

Some offer rates of top up for half the price and others just offer at the normal rate.

I know the night markets are always a little buyer beware, but what exactly is the gain they get from refilling other people's prepaid numbers. I guess I can see the privacy intrusion that may be in question providing your cell number to them, but I see these guys night after night with full lists of numbers they aided in topping up.

While I can't really figure out how some of them sell SIMS and top up for cut rates, I see locals hit these guys up regularly to get their phones recharged.

Anyone know what the rub is here?

Sent from my SCH-I535 using Thaivisa Connect Thailand mobile app

I'd have to see the actual top-up instrument to be sure but my best guess is that these top-up instruments (stored value with a scratch off PIN) and SIMs were promotional items, or inventory in the retail/wholesale channel - say of a shop/distributor which closed or needs cash, and thus liquidated perhaps even to cove a debt.

Whenever I've looked at the SIMs for sale on the street, the "activate by" date is close in or may have expired.

Service providers here more or less give SIMs away for free, so unless there is some bundled service/promotion of significant value embedded - like a 7 day/1 GB data plan, or some number of voice minutes - then a SIM should rarely cost more than 50 baht.