There is always a downside though. Many HTC Sensation owners out there rooted their devices and started flashing AOSP ROMs, and more recently stock based ROM’s. The issue of not having a working Wi-Fi calling app may have caused you a little grief. If your ROM developer hasn’t already solved the issue for you, XDA member bigmoew has. He took the apk, fixed it up and made it into a nice little update.zip file for you to flash to your Sensation. You would need to be sure to uninstall any current version of the app before flashing it though.
The mod comes in two forms, one specifically for AOSP users and one for Stock Users. Make sure you know what you have before you start flashing things and always make a back up before doing so, just in case. He has tested this on OrDroid 5.0.0, it should also work on the more recent 8.2.0 update too, and everything is up and working perfectly. If you have been missing the feature on your modded and much better Sensation, please don’t hesitate to check out bigmoem’s XDA thread for instructions and the file. One last thing before you run off, this is only for the SENSATION, not any other Tmo device.