Ask HN: Cheap VOIP call forwarding options

Hello HNers!

I was wondering if for the US market, there is any service which allows for cheap call forwarding. We are issuing a new business phone number but we map this new business phone number to an existing cell number. The cost of call forwarding is about 2-3 cents on Twilio/Nexmo and Plivo. I was wondering if there was a cheaper mechanism to do call forwarding? Like setting up your own gateway? Has anyone had any luck with this?