---
"@context": https://schema.org
"@type": TechArticle
"@id": https://www.twilio.com/docs/api/errors/13243#article
headline: "13243: Dial->SIP: Invalid SIP URI"
url: https://www.twilio.com/docs/api/errors/13243
inLanguage: en
dateModified: 2026-06-08T11:38:30.000Z
author:
  "@type": Organization
  name: Twilio Developer Education Team
publisher:
  "@type": Organization
  name: Twilio
---

# 13243: Dial->SIP: Invalid SIP URI

Log Level: WARNING

## Description

This warning occurs when the value in the `<Sip>` noun is not formatted as a valid SIP URI. Provide a valid SIP URI that is fewer than 255 characters.

### Possible causes

* The `<Sip>` noun does not contain a valid SIP URI such as `sip:jack@example.com`.
* The SIP URI is longer than 255 characters.
* SIP URI parameters or custom headers were appended with invalid syntax, which makes the full SIP URI invalid.

### Possible solutions

* Update the `<Sip>` value to a valid SIP URI such as `sip:jack@example.com`.
* Shorten the SIP URI so the full value stays under 255 characters.
* If you need to set transport, add it as a SIP URI parameter such as `sip:jack@example.com;transport=tcp` or `sip:jack@example.com;transport=tls`.
* If you need to add custom headers, append them after `?` and encode reserved characters as needed.

#### Additional resources

* [TwiML Voice: `<Sip>`](/docs/voice/twiml/sip)
* [Making SIP Calls](/docs/voice/api/sip-making-calls)
* [Use SIP with Twilio Voice](/docs/voice/api/sip-interface)