---
page_type: error
code: 13223
message: "13223: Dial: Invalid phone number format"
level: WARNING
product: Programmable Voice
---

## Description

Phone Numbers must be in E.164 format. E.164 numbers are formatted \[+] \[country code] \[subscriber number including area code] and can have a maximum of 15 digits.

### Possible Causes

- The phone number you are attempting to dial is not in E.164 format
- The `<Number>` noun inside your `<Dial>` TwiML instructions is not present
- You are attempting to dial something that is not a phone number

### Possible Solutions

Check the format of the phone number inside your `<Dial><Number>` TwiML.

Verify that the number is in [E.164 format](/docs/glossary/what-e164):

- Includes the country code
- Includes the area code
- Does not exceed 15 digits
- Does not include any invalid characters, like hyphens or parentheses

In your TwiML instructions, the phone number must be between the opening and closing `<Number>` tags, which are nested within `<Dial>`'s opening and closing tags:

```
<Dial><Number>+15555555555</Number></Dial>
```

If you are attempting to `<Dial>` an SDK end-user, ensure you're using the `<Client>` noun inside your `<Dial>` tags.

If you are attempting to `<Dial>` a SIP endpoint, ensure you're using the `<Sip>` noun inside your `<Dial>` tags.

For more information, read the [`<Dial>` docs](/docs/voice/twiml/dial).