You can decide to send sms codes only within your country. You decide whether the tradeoff between costs, privacy and features is worth it. Sending 150 sms a month (or a magnitude more) would cost me 0 €. I find some of the premium features worth paying for. But I would never relay OTP codes for telegram

I send thousands of SMS per month with a cost of zero. Even international.

It’s all included in my $40/mo plan.