Laravel 5.6 - Validate Numbers and spaces

In Laravel 5.6 I am validating alphabetic characters and spaces only in regex like this..

'name' => 'required|regex:/^[\pL\s\-]+$/u',

This works as far as I can see, I am now trying to validate numbers only and spaces like this..

'telephone' => 'required|regex:/[0-9 ]+/',

But this is not working and allows me to enter 'f4' where it should fail.

Where am I going wrong?

via Chebli Mohamed