AI phone calls
Place and receive phone calls from an AI agent or a backend application. Connect the calls to your tools and workflows through the same API.
Read the docs ↗About Hail
Hail is a communications platform for AI agents and backend applications to send and receive email, SMS, and agentic phone calls.
What Hail does
SMS conversations
Send and receive text messages through the same platform as your calls. Use SMS for follow-ups, notifications, and conversations that do not need a phone call.
SMS API page ↗Email for your application
Send, receive, and thread email from your backend or AI agent. Connect your own domain when mail must come from your business.
Email API page ↗What makes Hail different
Voice, SMS, and email
Hail provides voice, SMS, and email in one platform. Your application does not need a separate integration for each channel.
MCP server, REST API, and CLI
Use the MCP server, REST API, or CLI. Start from an agent client, or connect Hail to your application code.
One prepaid balance for all channels
Calls, texts, and email use the same prepaid balance. Hail has no platform subscription. Dedicated phone numbers have a recurring rental charge in addition to usage.
Automatic number purchase
Hail compares availability, price, and verification requirements across its carriers. It buys the cheapest number that is ready to use. Where a country requires verification, Hail collects the required information, files it, and completes the purchase after approval.
A self-hosted option
The platform source is available under AGPLv3. Run it on your own infrastructure, or use the hosted service operated by Hail HQ.
Free tools and a model pricing database
Hail publishes a model pricing database and free tools for voice cost, SMS segments, and email deliverability. Use them to estimate usage and check your setup before you integrate Hail.
Compare Hail with Twilio, Vonage, and AgentMail, or use the free tools.
Who uses Hail
Hail is built for these workflows and teams:
- Backend developers adding email, SMS, and AI phone calls to applications, services, and automated workflows.
- Developers adding phone, SMS, or email tools to an AI agent.
- Teams building support and operations workflows that contact people by phone, SMS, or email.
- Builders connecting agent clients through MCP, or integrating communications through an API or CLI.
- Engineering teams that want the option to run their communications platform on their own infrastructure.
The Hail team
Hail was founded in 2025 in Sweden. Hail HQ builds and operates the hosted Hail platform.
You can follow the project on GitHub and the founder on X, or send email to hi@hail.so.
How Hail works
Connect your application
Create an account. Connect your backend through the REST API or CLI, or connect your agent through MCP. The integration guides show examples for agent frameworks.
Set up your channels
For phone calls and SMS, pick a country and Hail buys a number for you. For email, connect your domain. Messaging registration and domain setup can affect when a channel is ready.
Fund usage and start communicating
Add prepaid credit. Your application can then send and receive email, SMS, and AI phone calls through Hail. The pricing page lists the current rates.
Key facts
- Company / operator
- Hail HQ
- Product
- Hail
- Founded
- 2025, Sweden
- Founder
- @redouaneoachour
- Type
- Hosted developer platform and open-source software
- Website
- hail.so
- Core offering
- Communications for AI agents and backend applications
- Services
- Inbound and outbound AI phone calls, SMS, and threaded email
- Interfaces
- MCP server, REST API, and CLI
- Pricing
- Usage is prepaid. Dedicated number rental is billed separately. See pricing.
- Contract terms
- Hail has no platform subscription. The hosted service terms apply.
- Self-hosting
- AGPLv3; independently operated by the party running it
- Communication
- hi@hail.so
- Alternatives
- Compare Hail with other providers
Frequently asked questions
Do I need an AI agent to use Hail?
No. Any backend can use Hail to send and receive email, SMS, and AI phone calls through the REST API or CLI. MCP is an additional integration option for AI agent clients.
Is Hail a hosted service or open source?
Hail is both. Hail HQ operates the hosted cloud service, and the platform is available under AGPLv3 for self-hosting.
Which carrier provides my number?
Hail works with several carriers. For each purchase, Hail compares price, availability, and verification requirements. You can select a specific provider in the advanced settings.
How does pricing work?
The hosted service uses a prepaid balance for calls, texts, and email. Dedicated phone numbers have a recurring rental charge. The pricing page lists current rates.
Can I use my existing agent?
Connect an MCP-compatible client or integrate the REST API or CLI into your application. The integrations page and docs show the supported connection paths.
How do I contact the team?
Email hi@hail.so for product questions, support, or a discussion about your integration. Include the channel and workflow that you want to build.