At least where I live, there is simply no option for voice/SMS SIM cards other than a subscription drawing from your credit card or bank account etc. So it would take the proxy person to also hold a bank account or credit card and be on the hook for any charges to the SIM card. Even with government ID etc they can't just go to a shop and pick up a prepaid for cash.

Theoretically possible, yes, but in practice, I think the only option is if you have the "right" connections with organized crime. I don't think you'd be able to solicit on the streets, even in the capital.