The Samsung SPH-A640 is a tri-mode dual band cellular telephone developed for PCS

Personal Communications Service

At the most basic level Personal Communications Service or PCS describes a set of wireless communications capabilities that allows some combination of terminal mobility, personal mobility, and service profile management...

 carriers like Sprint Nextel

Sprint Nextel

Sprint Nextel Corporation is an American telecommunications company based in Overland Park, Kansas. The company owns and operates Sprint, the third largest wireless telecommunications network in the United States, with 53.4 million customers, behind Verizon Wireless and AT&T Mobility...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 and Virgin Mobile

Virgin Mobile Canada

Virgin Mobile Canada is a cellular telephone company that was launched on March 1, 2005 as a joint venture between Virgin Group and Bell Canada. Since May 7, 2009, it is now a wholly owned subsidiary of Bell Mobility. - Pre-launch :...

 in Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

.
It contains an internal antenna, but removing a protector behind the battery slot reveals an external antenna slot.

The A640 has features that include SMS messaging and Push to talk

Push to talk

Push-to-talk , also known as Press-to-Transmit, is a method of conversing on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode....

 walkie-talkie technology, built-in camera, voice recognition and Bluetooth

Bluetooth

Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...

 technology, depending on the carrier. The A640 has an internal 65k ufb, 1.82 inch display with external Organic LED display.

The A640 does not have MP3 or video recording capabilities.

With dimensions of 3.6 x 1.8 x 0.09 inches and weighing 3.2 ounces, the Samsung

Samsung

The Samsung Group is a South Korean multinational conglomerate corporation headquartered in Samsung Town, Seoul, South Korea...

 SPH-A640 comes with a Standard 800 mAh

MAH

The National Security Service was the governmental intelligence organization of Turkey between 1926 and 1965, when it was replaced by the National Intelligence Organization ....

 Li-Ion Battery, Travel Charger, and User Manual. This device was released in mid to late 2006 in most areas in the United States and other countries such as Canada.

There is no way to unlock this device for use on other networks besides the specific CDMA network for which the phone was built.