# Mobile Client External Chat Overview

External Chat brings customer conversations from several messaging channels, such as SMS (Short Message Service) and social media, into a single inbox on the Cloud Voice App mobile client. Instead of switching between separate apps, you read and answer every inbound query from one screen.

:::note
This overview explains what External Chat does and what it needs to run. It is a feature for handling customer messages, not internal chat between colleagues.
:::

## Requirements

Before you can use External Chat, both the server and your app need to meet a few conditions.

:::note
The server-side checks below are managed by your system administrator, not from the app. Ask them to confirm the version, plan, and messaging setup before you expect the feature to work.
:::

**PBX (Private Branch Exchange) server**, the phone-system server your account runs on. Ask your system administrator to confirm the following:

- **Version**: 84.20.0.21 or later.
- **Plan**: Enterprise Plan or Ultimate Plan.
- **Messaging**: at least one messaging channel has been configured on the server.

**Cloud Voice App mobile client**: make sure your app is up to date:

- **iOS**: version 5.17.8 or later.
- **Android**: version 5.17.9 or later.

:::caution
External Chat only appears when every requirement above is met, including the app version. If you do not see it, update the Cloud Voice App and confirm the server version, plan, and messaging channel with your administrator.
:::

## Channel types

Each external chat carries an icon that tells you which channel the message came from:

- ![SMS channel](/images/pbx/sms.png) SMS
- ![WhatsApp channel](/images/pbx/wa.png) WhatsApp
- ![Facebook channel](/images/pbx/facebook.png) Facebook
- ![Live Chat channel](/images/pbx/live-chat.png) Live Chat

## Restrictions

Some rules apply to every channel:

- **Chat type**: both one-to-one conversations and group chats with a queue of agents are supported.
- **Session auto-closure**: whether and when a session closes on its own depends on how your system administrator has configured it.
- **File retention**: shared files are kept for 72 hours.

Other limits vary by channel. On SMS you can both reply to inbound messages and start a new session yourself. On WhatsApp, Facebook, and Live Chat you can receive and reply to a customer's messages, but you cannot open a session first.

:::note
On WhatsApp, Facebook, and Live Chat the customer has to message you before a session exists. Do not expect to reach a customer first on those channels. Only SMS lets you begin the conversation.
:::

| Channel | Start a session | Maximum file size |
|---|---|---|
| SMS | Yes | 100 MB |
| WhatsApp | Reply only | 100 MB |
| Facebook | Reply only | 25 MB |
| Live Chat | Reply only | 10 MB |

:::caution
Each channel has its own file-size cap (100 MB, 25 MB, or 10 MB). Sending a file larger than the channel's limit will fail, so check the limit before attaching large files.
:::

:::caution
Shared files are automatically removed after 72 hours. If a customer sends something you need to keep, download it before that window closes.
:::

## Highlights

- **One inbox for everything**: collect and work through queries from every messaging channel in a single place.
- **Reach customers on a business number**: message customers from a business phone number and keep your personal number private.
- **Hand off without losing context**: transfer a session to a colleague, who can see the full chat history and pick up where you left off.
- **Manage sessions your way**: escalate a chat to a phone call, archive or unarchive sessions, and more.
- **Notifications on your terms**: turn message push alerts and sounds on or off to suit you.

:::tip
Messaging always goes out from the business number, so your personal number stays private. If a chat gets complicated, you can escalate it straight to a phone call without leaving the session.
:::

## Next steps

Once the requirements are in place, you can start a messaging session with a customer and manage incoming queries from your external channels directly in the Cloud Voice App.