TRP is not used for that function. It is used to remark traffic or traverse VRF tables.
You need to either use ASA Phone Proxy; or, tunnel the phone with another device such as an ISR or ASA. I'm not a big fan of phone proxy (it sucks) so for now I would recommend an ISR881 or ASA5505 with DMVPN or EasyVPN to the head end.