---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/13120#article
headline: "13120: Annotate->BillingReferenceTag cannot be over 128 characters"
url: https://www.twilio.com/docs/api/errors/13120
inLanguage: en
dateModified: 2026-06-08T11:29:20.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 13120: Annotate->BillingReferenceTag cannot be over 128 characters

Log Level: ERROR

## Description

Twilio returns this error when your Voice TwiML includes a `BillingReferenceTag` value longer than 128 characters. Twilio parses and executes the TwiML your application returns for a voice call. If Twilio cannot process that request because the TwiML is invalid, Twilio logs the event as an error.

### Possible causes

* The `BillingReferenceTag` value in your `Annotate` instruction is longer than 128 characters.
* Your webhook returned TwiML that Twilio could not process because the `BillingReferenceTag` value exceeded the allowed limit.

### Possible solutions

* Shorten the `BillingReferenceTag` value so it is 128 characters or fewer before you return the TwiML response.
* Review the TwiML your application generates and make sure the `BillingReferenceTag` value stays within the allowed length every time you build the response.
* Check the Twilio Debugger for the failed request and inspect the returned TwiML so you can correct the invalid value.
* Open the webhook URL in your browser or test client and verify that the response does not include an oversized `BillingReferenceTag`.

#### Additional resources

* [TwiML for Programmable Voice](/docs/voice/twiml)
* [Twilio Debugger](/docs/usage/troubleshooting/debugging-your-application)
* [Programmable Voice](/docs/voice)