How do I set "Over the Phone" number for Agents?

How do I set "Over the Phone" number for Agents?

I cannot seem to properly configure my Agents so they can use "Over the Phone" status on their profiles. They receive the message "An 'Over the phone' number has not yet been set up for your account. Please contact your administrator". Absolutely cannot find this setting anywhere. Currently using Twilio for phone integration that works great in "Over the Web" mode.