HP has recently released a ROM update to the 65xx range of devices.
Before you ask... no this is not an update to Windows Mobile 5.0 - This update fixes a number of issues such as:
Fixes issue where an incorrect Cellular Service Provider Name was displayed after inserting a Subscriber Identification Module (SIM) from a different Service Provider.
Fixes issue where a blank screen was displayed when a SIM card, which has SIM Tool Kit enabled, is inserted.
Fixes issue with 32K SIM card (Swisscom) where Unstructured Supplementary Service Data (USSD) commands were not supported.
Fixes issue where the connecting ring tone was louder when using a headset to place an outgoing call.
Fixes memory leakage issue in the GSM radio firmware that may have contributed to occasional disconnected calls and an inability to place outgoing calls.
Fixes issue where user could not disconnect an active SIM Tool Kit call.
Fixes issue where some Call Barring Settings could not be activated or deactivated and Call Barring Status could not be read using Supplementary Services strings
You can download it from: