> ## Documentation Index
> Fetch the complete documentation index at: https://docs.zavu.dev/llms.txt
> Use this file to discover all available pages before exploring further.
# Egress & Fallback
> How a WhatsApp Alternative number reaches WhatsApp: the managed Zavu residential proxy, your own Android device, and automatic fallback between them.
WhatsApp watches the network path a linked number connects from. To keep a number healthy, every WhatsApp Alternative session egresses through an **in-country residential IP** and always appears from the **same exit** — never a datacenter or server IP, which is a fast route to a block.
You choose how the number reaches WhatsApp with the session's `egress`.
Direct egress (connecting from a server / datacenter IP) is not supported and can never be set — it is a guaranteed block. Every session must use either the Zavu residential proxy or an Android egress device.
## Egress options
**`external` — default.** Zavu routes the number through a managed in-country residential IP, geo-matched to the number's country and pinned stable per session. Metered and billed per GB.
**`android`.** The number egresses through a phone you control, running the Zavu Egress Node app. Uses the device's own connection — no per-GB charge.
### Set the egress on a session
Pass `egress` when creating a session, or change it later with `POST /v1/whatsapp-alt/sessions/{sessionId}/egress`. It takes effect on the next connect.
```bash Zavu proxy (default) theme={null}
curl -X POST https://api.zavu.dev/v1/whatsapp-alt/sessions \
-H "Authorization: Bearer $ZAVU_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"displayName": "Support line",
"egress": { "kind": "external", "country": "cl" }
}'
```
```bash Android device theme={null}
curl -X POST https://api.zavu.dev/v1/whatsapp-alt/sessions \
-H "Authorization: Bearer $ZAVU_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"displayName": "Support line",
"egress": { "kind": "android", "nodeId": "nd_abc123" }
}'
```
`country` is optional — when omitted, Zavu derives it from the number so the exit matches the number's own country.
## Is the managed proxy available?
Check whether the managed Zavu proxy is currently offered for your team before defaulting to it:
```bash cURL theme={null}
curl https://api.zavu.dev/v1/whatsapp-alt/proxy-status \
-H "Authorization: Bearer $ZAVU_API_KEY"
```
```typescript TypeScript theme={null}
const { zavuProxyAvailable } = await zavu.whatsappAlt.proxyStatus();
```
When `zavuProxyAvailable` is `false`, pair an Android egress node instead.
## Pairing an Android egress node
An egress node is a phone running the Zavu Egress Node app that lends its connection to a sender's sessions.
Register a node for a sender. The response includes a short-lived pairing payload (`token`, `gatewayUrl`, `wsPath`).
```bash theme={null}
curl -X POST https://api.zavu.dev/v1/whatsapp-alt/egress-nodes \
-H "Authorization: Bearer $ZAVU_API_KEY" \
-H "Content-Type: application/json" \
-d '{ "senderId": "sender_12345", "label": "Store phone" }'
```
Encode `token`, `gatewayUrl`, and `wsPath` into a QR and scan it from the Zavu Egress Node Android app. The token isn't stored — re-issue it with `POST /v1/whatsapp-alt/egress-nodes/{nodeId}/pairing-token` to show the QR again.
Once the node is `online`, set a session's egress to `{ "kind": "android", "nodeId": "" }`.
Node status is `pending` (paired but never connected), `online` (tunnel live), or `offline` (last tunnel dropped). List a sender's nodes with `GET /v1/whatsapp-alt/egress-nodes?senderId=...`, and revoke one with `DELETE /v1/whatsapp-alt/egress-nodes/{nodeId}` (this also kills its live tunnel).
## Automatic fallback (stay 100% active)
An Android device can go offline — the phone loses signal, is powered off overnight, or changes networks. When you run a session on an Android node, Zavu can **automatically fall back to the managed Zavu proxy** so the number stays connected, then **switch back to the device** when it comes online again.
* While the fallback is active, traffic runs through the Zavu residential proxy and is billed per GB (see below).
* While on the Android device, there is no per-GB charge — it uses the device's own bandwidth.
* If the device is offline and fallback is not enabled, the session waits for the device to return without dropping the link (no re-scan needed).
This keeps a device-backed number available even while the device is unreachable, and you only pay for proxy GB during the fallback window.
## Per-GB billing
Traffic through the **Zavu residential proxy** (`external`, including active fallback) is metered and charged to your team balance per GB. Traffic through an **Android egress device** is not charged — it uses the device's own connection.
* The **per-GB rate depends on your plan**: it starts at **$2.99/GB** and decreases on higher plans (down to **$0.99/GB**). Your current rate and usage are shown in the dashboard.
* Only `external` proxy traffic is metered; `android` egress reports no billable bytes.
* Usage is measured in decimal GB and swept to your balance.
Use an Android egress device for cost-sensitive, steady numbers (no per-GB charge), and rely on the Zavu proxy — or fallback — when you need a managed exit or maximum uptime.
## Next steps
Create a session and link it to a sender.
Send on the `whatsapp_alt` channel and handle inbound webhooks.