---
title: "400 Bad Request Phone No. must not contain letters"
description: "400 Bad Request Phone No. must not contain letters"
keywords: "400 Bad Request Phone No. must not contain letters ODATA"
url: "https://myrapidi.com/wiki/400_bad_request_phone_no_must_not_contain_letters"
locale: "en"
published: "2025-03-06T19:15:18Z"
modified: "2025-03-06T19:15:59Z"
---

The error message indicates that a **REST API request** failed with a **400 Bad Request** status. Specifically, the response body states:

> `"Phone No. must not contain letters in Customer No.='C-009999'"`

This suggests that the **Phone\_No** field contains invalid characters (e.g., letters or extensions such as `"x4321"`), which the destination system does not accept.  
  
**The REST service returned a status code that is not 20x - i.e. not OK - Status code received: 400 Bad Request Response body: {"error":{"code":"Internal\_ServerError","message":"Phone No. must not contain letters in Customer No.='C-009999'. CorrelationId: 5a041048-ede7-4d6a-9193-3ef1508b5454."}} Data Sent to REST service: {"Phone\_No":"732-532-4444 x4321"} Error on connection NAVODATA001.**  
  
Solutions:

1. Use [##ISPHONE](https://wiki.myrapidi.com/wiki/isphone) formula to validate the phone number format and ensure that you do not send incorrect data to the destination system.
2. **User Validation** : Implement validation rules to prevent users from entering invalid phone formats.
3. **Pre-Processing Before API Call** : Add a script or logic in your integration to clean the `Phone_No` field before sending it.