textbee is an open-source SMS gateway that uses an Android phone and its SIM to send and receive SMS. Your code calls a REST API, the API pushes each message to the phone, and incoming texts come back through the API, dashboard or webhooks. It is built by Nuver Labs, and the NestJS API, Next.js dashboard and Kotlin app are MIT at github.com/textbee/textbee. The app is an APK from textbee.dev, not the Play Store.
Self-hosting with Docker Compose is free; you supply the server, phones and SIM plans. Hosted plans: Free with 1 device, 50 messages a day and 300 a month; Pro at $14.99 a month or $99.99 a year with 5 devices and 5,000 messages a month; Scale at $29.99 a month or $199.99 a year with 15 devices and 25,000 messages. Custom plans are quoted.
textbee has no iMessage or RCS. It sends SMS from your own phones and numbers and can be self-hosted. Linq is a managed service for iMessage, RCS and SMS from $260 a month on Pro, and cannot be self-hosted.
Developers and small businesses sending reminders, alerts and OTP codes from their own number.