Won't work in practice. We tried that, and (scum)phone companies apply arbitrary filters to SMS sent with 'unlimited plans', not delivering messages which they don't like. Experiments have shown that SMSs with random text arrive in 80-90% of cases, but if they contain words like 'verification', 'code', 'код', еtc, only about 10% do reach the recipients.

Of course, these same operators offer commercial rates for delivering 'branded' messages at a far higher rates.