Hewlett-Packard's iPaq 510 Voice Messenger dual-mode smart phone is shipping, five months after it was announced.

It will be sold unlocked from a specified carrier's service for $299 to $349, although HP plans to work with carriers to bundle the phone with their services, an HP official said in February.

The 510 is the first device in a new line of HP smart phones to be unveiled in coming months, an HP spokeswoman said.

In addition to operating in both Wi-Fi and cellular networks, it provides more than 20 voice commands to allow hands-free operations for mobile workers. Users can reply to email with a voice response without typing, she said. A Bluetooth headset will allow users to listen to email and text messages through a text-to-voice feature.

The 510 operates on the Windows Mobile 6 operating system and includes 12 function keys, rather than a full QWERTY keyboard as is commonly seen on other smart phones.

HP said that up to six hours of continuous talk time are possible on a fully charged battery. It is the first iPaq device to allow IT managers to manage the device over the air, HP said.