Unable to verify phone number

[Drifters]

I have someone who's trying to leave me rep for a completed sale, and he says it won't allow him to leave rep until he verifies his phone number, but says there's no option to verify.

Need help on how to walk him through this.

 

[EpicNPC]

To verify a phone, it's the big green box at the top of the site. Can't miss it, it's on every page.