[pstation]

In other countries these setups are fairly illegal because it bypasses the international call tariffs that the typically state owned telco company would be entitled to. A local domestic call might cost $.01 per minute and an international call $.20. They call it "bypass fraud".

But in the US, I'm not so sure since things are already deregulated.

[toast0]

US doesn't really have bypass fraud as a category, no; there's no real pricing difference based on the source of a call. Inbound international calls don't have to pay extra termination costs vs domestic calls and outbound international calls aren't paying much more than the cost of a local call + whatever the foreign carrier charges for termination. If you were doing bypass fraud in another country for calls to/from the US, you don't need SIM farms in the US, because you could just get a SIP account.

These boxes would be used for pricing arbitrage where a mobile phone user can get 'unlimited' calling or messaging but a bulk messaging/calling customer would have to pay something per message or minute, or to avoid customer identification or restrictions on message that would happen with a bulk account.