I am not going to argue with you regarding the reasons you may want to record your incoming or outgoing calls, nor how it is illegal or only partially legal in some countries.
There are a couple of issues with full duplex phonecall recording on the untouched HD2:
- the other person’s voice is very faint and totally unhearable when speaking in loud environments
- the recording stops after a minute or so, and longer phonecalls are cut after that delay
The reasons for this are
- the sound for the third party is not recorded directly, but only what comes from the speaker through to the mic is hearable
- the device enters a sleep mode after a certain delay when in a phonecall, so anything which is not radio related is shut down
The main concern until a while ago was the first problem, the second being addressed by a pre-existing registry hack by I don’t really know who (I’d be happy to credit them, but XDA member shinoby_uk only released a CAB of those pre-esisting hacks, so he is not the real author); this neverending issue (which in time led some people to think that it was a hardware limitation, while I’ve always believed in the hidden software switch) has been solved (according to the XDA member who published the solution) by 4pda.ru member RekGRpth; the existing registry hacks that were released by XDA member mskip (if I am not wrong) and worked for previous HTC models, are still needed, even if are not sufficient by themselves to enable full recording.
So here is the complete list of registry keys to add/modify in order to enable full 2way incall recording on the HD2:
[HKLM > Drivers > BuiltIn > WaveDev] "MixModeRecord"=dword:00000001 [HKLM > Drivers > BuiltIn > RIL] "BatteryTimeoutInCall"=dword:00000000 "BattSuspendTimeoutInCall"=dword:00000000 "EnableFastDormantDisplayDuringCall"=dword:00000000 [HKCU > ControlPanel > Phone] "Sleep"=dword:00000000 [HKCU > ControlPanel > BackLight] "LightSensorPollingEnable"=dword:0 [HKLM > System > AudioRecording] "Enabled"=dword:00000001 [HKLM > Software > Microsoft > Voice] "EnableCallRecordMenuItem"=dword:00000001 "AllowInCallRecording"=dword:00000001
Once you have done so, you are still not done, as you will need a program to actually record the calls; the one I use is the simple but deadly efficient ACR by XDA member slothie.