The regex for a phone number isn't working

I have a regex for a phone number, but when I test it in a WordPress form it doesn't work. The regex is: [/^(02|03|04|07|08)\d{8}$/]. By the way it is an Australian phone number and the phone number should like something like this 0267555888, when entered into the form. Could someone please tell me why this isn't working for me? Thanks in advance.

Drop the outer []s.