A common complaint with the HD2′s in-built call recording software is that it is incapable of recording both sides of the conversation effectively. Luckily, XDA forumer korand found a handy tip while browsing another site.
To activate two-way in-call recording, simply change the following registry key in your phone:
Registry editing can be done through programs such as Total Commander and Resco Registry Editor. However, you must ensure that you only change the mentioned key as altering other keys could potentially make your device unusable.
You can follow discussion about the tweak in this thread._________