7-digit phone number - Completing Apple ID

Hello there. Please assist if you can.

I just purchased a new iPhone and I'm a first time user. I have not used my Apple ID in the App Store or iTunes yet.

I am trying to sign in to iTunes, I get this pop up message: 'This apple ID has not yet been used with the iTunes Store. Please review your account information'. So I click on 'Review'. I see a form where I select my country, Papua New Guinea, and then check the agree to terms and conditions check box. I then hit the continue button.

I now come to this page (see below). I fill in all information, including my phone number.

When I click on continue, I get the message in red that the phone number must be a 7-digit number.

My phone number has 8 digits. I can't get passed this section.

Please, anyone, assist.

Thanks for your time.