@warrior_king First you have to activate Phone System in Teams and get a phone number. Depending were you are located you can get a number from Microsoft using Calling Plans or you can get a number from any other operator via Direct Routing.
https://products.office.com/en-us/microsoft-teams/voice-calling
When you have a phone number in Teams you can get your landline calls into Teams, but instead of forwarding calls you might want to move your number into Teams. But you still the Phone System license with Calling Plans or Direct Routing.
