iPhone time zone keeps changing to GMT or Cupertino time

The iPhone may ship worldwide, but some units apparently want to go home to Cupertino. Several devices are exhibiting an issue in which the time zone setting persistently reverts to U.S. Pacific Coast time or GMT.

In some cases, this issue can be resolved by updating to iPhone OS 2.0.2.

In other cases, the following procedure may be required:

1. Turn off the phone
2. Take out the SIM card
3. Replace the SIM card
4. Turn on the phone
5. In Settings, Reset All Settings
6. Set the correct time zone