# Memory across channels (/docs/caller-memory/channels)

> How phone calls, web calls and chat, and WhatsApp share one memory of each caller, and how callers are recognized.

A caller has one memory per [Memory pool](/docs/caller-memory/memory-pools), whichever way
they reach you. What they tell your phone agent is known to your WhatsApp assistant on the
same pool, and the other way round.

## How callers are recognized [#how-callers-are-recognized]

| Channel                            | Recognized by                              |
| ---------------------------------- | ------------------------------------------ |
| Phone calls (inbound and outbound) | Phone number                               |
| WhatsApp                           | Phone number                               |
| SMS                                | Phone number                               |
| Web calls and web chat             | Email address, when your page provides one |

The same phone number is the same person across calls, WhatsApp, and SMS, whatever format it
arrives in. A web visitor is recognized when your page passes their email address as
`email`, `user_email`, `customer_email`, or `contact_email`. Without an email, a web
conversation is not remembered.

When a conversation carries both a phone number and an email, the caller's record gains
the one it was missing. If the two point at different records, nothing is merged
automatically; the caller is flagged as an **identity conflict** for you to review. See
[View and manage memory](/docs/caller-memory/manage#identity-conflicts).

## Phone and web calls [#phone-and-web-calls]

* **Returning callers are greeted naturally.** Instead of the standard welcome message, the
  agent recognizes the caller, refers to one thing from last time, and moves the
  conversation forward. Your welcome message is still used as a guide for tone and content.
* **Recent WhatsApp messages come along.** Messages exchanged since the memory was last
  updated are shown to the agent with their times, so a call right after a chat already
  knows what was said.
* **The memory is updated after the call**, together with any WhatsApp messages waiting to be
  added.

## WhatsApp [#whatsapp]

* **Every reply knows the caller.** The WhatsApp assistant reads the caller's memory before
  each reply, so it can use what was said on a call yesterday.
* **Messages are kept word for word until they are added.** Once enough new messages have
  built up, including your templates and your team's replies, they are folded into the
  memory. A call in the meantime folds them in straight away.
* **A newer call wins.** If the caller called after the last chat message, the next reply
  follows the call.
* **Templates and your team's messages count.** If you send a template and the caller replies
  "OK, thanks", the memory records that they received it.

<img alt="The Recent interactions of a caller, listing three phone conversations with the time, direction, agent, and outcome of each" src="__img0" />