---
title: Transport contracts
description: Implement a channel transport to integrate a provider not shipped by sently.
icon: FileType
source: "src/core/types.ts"
---

| Contract | Required method | Optional methods |
| --- | --- | --- |
| `Transport` | `send(MailOptions)` | `sendBatch`, `verify`, `close` |
| `SmsTransport` | `send(SmsOptions)` | `verify`, `close` |
| `WhatsAppTransport` | `send(WhatsAppOptions)` | `verify`, `close` |
| `PushTransport` | `send(PushOptions)` | `verify`, `close` |

Each contract can expose a stable optional `provider` identifier for hooks and observability.

<Cards><Card title="Channels" href="/docs/channels" /></Cards>