UC500.com Cisco CallManager Express, UC500 reference

The default behavior for an FXS port (a port that you connect an analog phone or fax to)  on a cisco router is to act as a gateway port that is configured with h.323 in CallManager Express. 

We can make the FXS port act just like a SCCP controlled phone like a VG224 port or phone connected to an analog telephony adapter.  This way you can control the phone in CallManager express and use CME to manage hunting and other features.

Cisco has a configuration guide for STCAPP at This Link

Below is a sample working configuration:
sccp local FastEthernet0/0.15
sccp ccm 10.15.0.1 identifier 10
sccp ccm 10.10.0.1 identifier 12
sccp
!
sccp ccm group 1
associate ccm 10 priority 1
associate ccm 12 priority 2
associate ccm 30 priority 3
switchback method graceful
stcapp ccm-group 1
stcapp
!
dial-peer voice 3 pots
service stcapp
port 0/1/0
!
voice-port 0/1/0
caller-id enable