---
title: Platform Variables
slug: mcp-server/platform-variables
docTags: 
createdAt: 2026-05-27T07:51:20.416Z
---

Platform variables are runtime values Exotel injects at call time. Use them in VoiceBot prompts and tool parameters to give your bot access to call context.

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## `{contact_uri}`

The SIP URI of the incoming caller. Contains the caller's phone number.

Use it in tool parameters when you want a notification or log entry to include who called:

:::BlockQuote
"Missed call from `{contact_uri}` — please follow up."
:::

At call time, `{contact_uri}` resolves to the caller's number in SIP URI format (e.g. `+919886752549@sip.exotel.com`). Most notification tools parse this automatically.

**Without it:** your bot has no way to surface the caller's number to downstream tools. Add it to any tool parameter where caller identity matters.

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*More variables will be documented here as they are confirmed.*