---
page_type: error
code: 31007
message: "31007: Twilio Client: Voice JavaScript SDK version not supported"
level: ERROR
product: Programmable Voice
---

## Description

Twilio Voice JavaScript SDK 1.x is deprecated. Expect intermittent disruptions to applications running Voice JavaScript SDK 1.x until the final shutdown September 10, 2025. Upgrade your application as soon as possible to avoid further disruptions.

### Possible Causes

- You are using Voice JavaScript SDK version 1.x in your application
- You are using Twilio Flex UI version 1.x in your contact center

### Possible Solutions

- Follow the [migration guide](/docs/voice/sdks/javascript/migrating-to-js-voice-sdk-20) to upgrade your application to Twilio Voice JavaScript SDK 2.x
- Follow the [Flex migration guide](/docs/flex/developer/ui/migration-guide) to upgrade your Flex instance to UI 2.x