Special thanks for RoidDroidVoid for testing and about using HTC-RIL 4.0.0012HMQ instead of the one included in CM9.
Download CM9 WiFi Calling Patch
Download MIUI V4 WiFi Calling Patch
Trip's build.prop with proper RIL settings
1) Copy file to your SD Card.
2) Reboot into Recovery.
3) Flash WiFi_Calling_Patch_CM9_ICS.zip for CM9 or WiFi_Calling_Patch_MIUI_V4.zip for MIUIV4
4) Reboot. Your done!
Edited by yousuc, 04 February 2012 - 04:12 AM.