Issue setting up Forti Soft Phone through FortiClient VPN

I have a Fortinet 101F firewall setup with VPN IPsec running. I have a FortiVoice 101, and I want to setup Fortiphone Softphone through the VPN. The Fortiphone Softphone runs fine with the LAN network, but when I try logging in through the VPN. I need some guidance to get it implemented please.