Show HN: Hail.so – Send and receive emails, calls, SMS via a single MCP/API/CLI

- Hail.so is an open-source tool (GitHub) that unifies email, SMS, and voice calling into a single API, CLI, and MCP (Model Context Protocol — a standard letting AI models like Claude directly invoke external tools). It is explicitly designed for AI agents that need to send messages or make calls. - It wraps several existing services: Twilio (telephony/SMS), AWS SES (email sending), LiveKit (real-time audio), ElevenLabs and Cartesia (AI voice synthesis), plus various LLM providers. The goal is to replace the usual messy setup of connecting these services separately. - The creator spent a year as CTO of an AI startup building voicebots for industrial companies; the project distills what they found most useful (automated calls, emails, SMS) into a single deployable backend. - This matters because building communication capabilities into AI agents currently requires stitching together multiple paid services, handling SIP telephony infrastructure, and managing separate dashboards and invoices. Hail aims to collapse that friction into one self-hostable or managed platform.