Boeing Co (BA.N) said on Wednesday it has begun offering a specialized mobile phone aimed at government agencies and contractors who need to keep communication and data secure.

The Boeing Black Smartphone is based on Google Inc's (GOOG.O) Android operating system and built into a black, tamper-proof handset capable of accessing multiple cell networks instead of a single network like a normal cellphone, according to Boeing and filings with the U.S. Federal Communications Commission.

The secure phone marks an extension of the communications arm of the Chicago-based aerospace and defense contractor, which is best known for jetliners and fighter planes.

Though the phone is not yet commercially available, Boeing is talking to potential customers after 36 months spent developing the device, said Boeing spokeswoman Rebecca Yeamans."

"We saw a need for our customers in a certain market space" that Boeing could meet with its technology expertise, she said.

Boeing is not naming wireless carriers and handset makers it is working with and not disclosing the price, she said.

The 5.2-by-2.7-inch handset, slightly larger than an iPhone, uses dual SIM cards and can operate on the WCDMA, GSM and LTE frequency bands. It also offers WiFi and Bluetooth connectivity and ports to allow "integrating additional sensors or technology enhancements like satellite connectivity or expanding power," Boeing said.

Word of the new phone appeared on tech sites last year, but the revelations Wednesday marked the first clear picture of the device. A video and product card on Boeing's website show how users can attach components to reach special networks, expand the battery or attach biometric sensors. The device is assembled in the United States, the website says.

Boeing designed the phone to be used "primarily by governmental agencies and their contractors to ensure that data and voice communications undertaken by their respective employees are transmitted and stored in a highly secure manner," the company said in the FCC filings. Boeing requested confidential treatment of details of the product in its application for FCC authorization of the equipment.

On its website, Boeing said the phone provides data encryption and uses a special architecture that "ensures the device starts in a trusted state, enabling maximum security of data."

In addition, "the Boeing Black phone is manufactured as a sealed device both with epoxy around the casing and with screws, the heads of which are covered with tamper proof covering to identify attempted disassembly," the FCC documents said.

"Any attempt to break open the casing of the device would trigger functions that would delete the data and software contained within the device and make the device inoperable."

A sample purchase contract submitted to the FCC says the phone would be sold directly by Boeing or its agents.

Yeamans said Boeing combined its own engineers with the talent of people who joined Boeing recently through acquisitions that included Argon ST Inc, Digital Receiver Technology Inc, Kestrel Enterprises Inc, Ravenwing Inc, and Solutions Made Simple Inc.