I'm on full or partial unbundling — does that change anything?

No: conditional forwarding is carried by the line itself, whether it belongs to the incumbent carrier or to unbundling — full or partial. The activation code gets dialed from your phone, and the test runs with you during setup. The only case to check: some boxes on full unbundling manage forwarding through the box's web interface rather than a code — we guide you either way. If forwarding is blocked, we tell you before any billing.