This should work on any 1.6.X Microsoft Voice Command and any WM 6.5 rom.
Start -> Settings -> Voice Command; select "Phone", press "Options", select "Announce incoming calls".
If your incoming announcements don't play, it's likely that VC is still working fine. You can test this by looking for this file on your device using FileExplorer.
My Device\Application Data\Volatile\TSCallerID.wav
Double tap the file to play it in Media Player, it should speak out the contents of it (last caller). If this works, then you know Voice Commander is working fine, its the phone not playing it.
If the file is there, then you can make it play by following this guide.
The problem with the call announcement on the TP/DIAMOND doesn't appear to be with Voice Command, but possibly with the phone software on the TP/DIAMOND - since Voice Command is generating the announcement file - it's just not being played.
The following registry changes might partially restore the call announcement, a short-term solution until something better comes along:
HKCU\ControlPanel\Sounds\TTSAnnounce\Category: change VoiceCommand1 to Ring
HKCU\ControlPanel\Sounds\TTSAnnounce\Script: change as5p to v0p (for vibrate and ring) or p (for ring only)
With this change, the ringtone will start - and then be interrupted with the calller ID/name announcement. (Assuming that call announcement has been enabled in Voice Command).
The voice now should work, but the volume for it is too low...
To increase the sound level:
HKCU\Control Panel\Sound Categories\Voice Command1\AttenutationCategory
I set it to 7, but I see no difference going louder. Using 0 or 1 will make it whisper quiet.
If that does not make it louder, then edit:
HKCU\Control Panel\Sound Categories\Ring\AttenutationCategory
Same thing, set to 7.
I didn't have to make any changes to InitVol registry settings as previous people stated.
Now the phone will speak callers name and phone type (IE, "home"), if my BT headset is enabled then it will spreak it over the headset instead.
I also like it better when the voice talks a little slower, as previously stated that can be changed by editing:
HKEY_CURRENT_USER\Software\Microsoft\Speech\Voices \DefaultTTSRate
Mine defaulted to 5, I dropped it to 2 which is normal speed for speaking.
Note: You need a registry editor on your mobile device, you don't have to reset when making edits.
Credit to: reefland, rprochnow, and phm registry editor.
HTC TOUCH DIAMOND & HTC TOUCH PRO CDMA/GSM