Twilio charges around $0.05–0.06 per SMS round-trip. Doesn't sound like much until you're building an MVP that sends reminders, confirmations, and notifications — suddenly you're looking at $50/month for a thousand messages. For an app that's not making money yet, that's a dumb tax. Here's what I did instead: grabbed a cheap Android phone, installed an open-source app called SMS Gateway for Android, and turned it into a full SMS gateway with a REST API. My SMS costs dropped to whatever my mobile...