The  T-Mobile G1  is an Internet-enabled 3G smartphone  with an operating system designed by Google and hardware designed by HTC. It was the first phone to the market that uses the Android mobile device platform   The phone is part of an open standards effort of the Open Handset Alliance.

The G1 runs the Android Operating System. Several applications that come installed with this device are:

    * Full HTML web browser powered by the WebKit rendering engine; it allows a maximum of 8 windows.

    * Gmail
    * Google Calendar
    * Google Maps
    * Google Talk
    * YouTube video player

In the United States, the carrier-subsidized firmware for the G1 also comes with an application for accessing the Amazon MP3 music store, which allows users to browse and legally purchase DRM-free songs; however, in developer firmwares this application is not included.More applications can be obtained through the Android Market application or directly through developers. Documents in Google Docs can be viewed, but not edited. However, spreadsheets in Google Docs including the texts in them can be edited.

Upon the launch of the T-Mobile G1, one concern among developers was that limitations were present in its build of Android that blocked superuser access to the phone. However, a severe vulnerability was soon discovered in early versions of the firmware — everything typed into the phone's keyboard was being interpreted as commands in a root shell.  By using tel netd  to exploit this, users could flash a modified image with root access. This process, dubbed "rooting" by the community,allows users to gain superuser access and perform actions previously impossible without root access, such as installing custom builds of Android, running Debian, installing custom themes, and enabling ad-hoc Wi-Fi tethering. Although Google and T-Mobile were quick to patch this vulnerability with update RC30, a ROM from HTC was later leaked allowing users to downgrade to an older firmware with the bug. The Android Dev Phone 1 comes with superuser access officially integrated into its firmware, allowing native code and custom kernels to be run without any special hacks

The G1 firmware can be updated by flashing  from an image stored on the microSD card.  These images are cryptographically signed by either the phone manufacturer or network carrier. Along with other features, support for widgets were introduced through updates. As of Friday, December 18, 2009, HTC and Rogers Wireless have both stated that they will not support Non-Google branded HTC Magic and HTC Dream phones past Android Version 1.5. HTC changed the content of its website to reflect this

T-mobile G1 Specs

# Storage: The HTC Dream has a microSD card slot and comes with a 1GB memory card (2GB in the UK, Germany and Canada). It has been confirmed to work with capacities up to 16GB, and may work with even larger cards.  When the USB cable is connected to a computer, this computer can access the card without removing it from the HTC Dream. The phone can access media files arranged in folders, but the folders have to be created from a third-party file management application or from a computer or a third-party file-manager program on the phone.
# Battery: The HTC Dream has a user-replaceable, 3.7V, 1150 mAh (4.25Whr) rechargeable lithium ion battery, which is advertised to offer up to 130 hours of standby power.
# Orientation and location: The HTC Dream provides an accelerometer for detecting movement and determining which direction is 'Up'. It also has a digital compass, giving it complete orientation data. The Dream includes a GPS receiver for fine-grained positioning, and can use cellular or wifi networks for coarse-grained positioning.
# Case: Three different colors are available: black, bronze, white.
# Connectivity: Wi-Fi (802.11b/g) using a Texas Instruments WL1251B chipset; Bluetooth 2.0+EDR via Texas Instruments BRF6300; ExtUSB with an SMSC USB3316 chipset; standalone GPS and A-GPS; Quad band GSM 850/900/1800/1900 MHz and GPRS/EDGE, plus Dual band UMTS Bands I and IV (1700 & 2100 MHz) and HSDPA/HSUPA  at 7.2/2 Mbit/s using the Qualcomm RTR6285
# CPU: The MSM7201A is an ARM-based, dual-core CPU/GPU from Qualcomm  and contains many built-in features, including 3G and a GPU capable of up to 4 million triangles/sec. It has hardware acceleration for Java,  but this does not accelerate execution of Android applications, as they are targeted to the Dalvik VM, not the Java VM.
# Keyboard: The HTC Dream has a sliding full 5 row QWERTY keyboard. It also comes with a set of 6 navigation buttons:

    * phone green, black  – make outbound calls, receive incoming calls, or open the dialer.
    * home black – displays home screen with shortcut icons for some applications and a drawer containing all applications on the phone.
    * trackball – navigate among items on the screen or scroll in text fields.
    * back (black) – return to the previous screen.
    * phone (red, black in UK) – end currently active call or put phone into sleep mode.
    * menu (black) – display the contextual menu for the current screen.
    * a touchscreen keyboard is available as of Android 1.5. Note: this feature does not work on phones sold to be used on the Rogers Wireless network.

# Side controls: A pair of volume buttons is located on the left side of the phone, and a camera button on the right side.
# Audio: In place of a headphone jack, the Dream like many HTC smartphones has a mini-USB-compatible ExtUSB jack that carries audio signals alongside the regular USB signals, and can be converted with a dongle (now shipped with the phone) to support any standard 3.5 mm headphone. The standard headset includes a clip-on microphone and call answer/hangup button. The Dream supports audio files in MP3, AAC, AAC+, WMA, MPEG4, WAV, MIDI, and Ogg formats