From Forum Nokia Wiki

In general, China Unicom has disabled many capabilities for untrusted 3rd-party applications, including

• platformRequest()
• Network connections
• Messaging
• PushRegistry
• Local connectivity
• PIM access (read and edit)
• UniJa 3D Graphics
• UniJa Standby Mode

There is no trusted 3rd-party domain.

One has to sign the MIDlet with a certificate from China Unicom. This operator domain has full access to all APIs.

There is also a China Unicom testing certificate available, which is valid for 21 days. It is required to apply again when the validity period is exceeded.