"If you are in an active call using bluetooth car kit or bluetooth headset and you receive a second incoming call and you let it ring or you ignore the incoming call, the call will be diverted to Voicemail. The first call remains active but you can no longer hear the caller (the caller can still hear you). The audio has been lost. If you answer the call and swap between calls or reject the call, the issue is not seen."
The update can be downloaded and installed from a microSD card or installed over-the-air at:
Since this update is a patch, and not a full ROM software upgrade, the patch will need to be reapplied if the Treo Pro is hard reset.