People I know in US telecom are not surprised by these SIM farms. These people are either:

a) Doing some weird grey market VoIP thing. 32-in-1 GSM to SIP gateways have been a thing for a very long time in the developing world. Maybe they think they found some arbitrage route for phone traffic to/from the US PSTN that they can profit from. Anyone who interacts with grey market voip stuff will recognize these things immediately.

b) Using them for something like receiving 2FA authentication codes to create bot/socketpuppet social media accounts. In this sort of scenario they'd have live phone numbers/service and the cheapest possible phone plan, and ability to receive incoming SMS. The accounts then get provided to some other group of people who are doing mass advertising/social media manipulation.

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zarzavat 2 hours ago | parent | next [-]

Regarding B, why would you create your sock puppets in the US instead of in some developing country where everything is a lot cheaper?

If they are using it for 2FA it's likely for some US-only service.

	▲	walrus01 32 minutes ago \| parent [-]
		"Authentic" US domestic resident sockpuppets for political or social manipulation. Combined with things like using residential proxies/relays through traffic on compromised routers on top-10 sized US last mile broadband providers such as Comcast, RCN. Google "residential proxies for sale" for some examples. Plenty of things like the various services run by Meta will treat your content differently if they know you're coming from a Bangladesh phone number and ISP vs. being what appears to be an authentic domestic USA human. Having live US phone numbers that can receive SMS for "is a live human receiving this code" verification purposes is also useful for many other kinds directly fraudulent activities.

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toast0 3 hours ago | parent | prev | next [-]

c) grey route outbound sms. Even cheap US plans tend to have 'unlimited' sms, sometimes even to selected foreign destinations. Sometimes carrier billed SMS is cheaper than aggregators (but not too often) or may have better routing to difficult destinations.

	▲	walrus01 2 hours ago \| parent [-]
		Yes, I can definitely see that being plausible, particularly if they've gone to the efforts to make software tooling to spread out the outbound SMS volume around many different SIM and self-rate limit their volume, to avoid getting cut off, rate limited, or account banned.

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kotaKat 3 hours ago | parent | prev [-]

To point A: I remember a long while ago making a 'free VoIP' call and my call routed into a MetroPCS recording telling me my service was suspended for nonpayment. Hung up, redialed, number shot through another dodgy route.

Good times!