CNAM can be set up only for US Plivo numbers because the CNAM database is available only in the US currently. However, CNAM registration works differently for Long Codes and Toll-Free numbers, so while the CNAM can be registered for Toll-Free numbers, however, there is no guarantee that CNAM will work even after the registration.
Long Codes: With a Long Code number there is a tag (Destination Point Code) on the number so the receiving phone carrier knows which National CNAM database to pull the CNAM from
Toll-Free: Toll-Free numbers do not have a tag (Destination Point Code), so the receiving phone carrier can only pull from their own internal database. So, even if Plivo does get CNAM registered, the CNAM will not work if all the receiving phone carriers do not update their database. This is an industry-wide restriction.
After CNAM is registered, the CNAM will be displayed on the destination handset if the end-operator and the handset support CNAM-feature.
To check if your plivo number has the CNAM feature you can reach out to our support team: https://support.plivo.com/support/home