When Clients use the Schedule Engine Live Voice product, they will need to have a call forwarding provider on their end. Below are some of the most common phone providers along with some help articles you can surface to the client!

Dialpad forwarding instructions: https://help.dialpad.com/hc/en-us/articles/115003405546-Manage-your-Dialpad-Devices#adding-a-forwarding-number

Ring Central Call Forwarding & Call Handling Knowledge Base: https://support.ringcentral.com/ca/en/mvp/phone/call-handling-forwarding.html

Ring Central: Setting up your call forwarding for after work hours

Ring Central: Forwarding calls when all phones are offline

Ring Central: Why are my calls not forwarding to third-party numbers?

Verizon: https://www.verizon.com/support/knowledge-base-220163/
verizon.com

Once Talk:View / Manage Call Forward Settings | Verizon: 

One Talk - Managing call forward settings from your desk phone, web portal or via the mobile app.Nextiva: Set Up Call Forwarding