[2][3] The Hiptop software was designed by Danger, Inc., which was located in Palo Alto, California, and purchased by Microsoft for $500 million in 2008.

This included a catalog of downloadable software applications, email hosting, instant messaging, web proxies and a cloud service for the entire personal data on the device.

[5][6][7] Screens on all Sidekick devices (excluding the Slide and 4G models) rotate 180 degrees 'up' to the open position on a patented[specify] hinge pin to reveal the qwerty keyboard.

[9] Released in 2004, the Hiptop2 was introduced with Danger moving the D-Pad (directional-pad) to the left side of the Hiptop (from the inside where it was previously found), along with top-left and top-right shoulder dials, volume up/down and power on bottom of phone.

[10][11] The industrial design was changed as well as a new color scheme to a dark gray shell with silver trim and gloss black buttons.

New features were introduced including a removable 3.7v 1500 mAh battery, a miniSD slot capable of up to 2 GB of flash memory storage, a 1.3-megapixel camera capable of 1280 x 1024 resolution, an improvement from the sub-megapixel VGA 640 x 480 camera, and a built-in 1/16" audio jack for the newly included MP3 playback software.

The built-in storage allows for end-users to store files for .mp3, .wav, and .aac playback, camera, user customizable themes and other catalog application's uses.

In early 2011, US regional carrier Cincinnati Bell began selling the Sidekick LX 2009 as the Sharp Jump.

These upgrades include 128 MB RAM and 225 MHz TI OMAP 850 processor, as opposed to the Sidekick 3 and LX's 64 MB RAM and 200 MHz OMAP 331 processor, and a second speaker which is located on the back of the device, as opposed to the Hiptop 3 and LX's reliance on the D-pad speaker for both calls and music playback.

[16] The new handset supports 3G and HSDPA, and makes various changes to the hardware, including a 3.2 inch F-WVGA display with 854×480 resolution and a 3.2-megapixel camera with autofocus and flash.

Support for Facebook, Twitter and MySpace is now native to the system, allowing the handset to pass along notifications in the status bar as it does with instant messaging, e-mail and so forth.

The highest-profile addition to the handset was Bing (then called "Live Search"), was added and integrated with the new GPS functionality; the mapping software previously relied on cell-tower triangulation (a far less accurate process).

While the T-Mobile Sidekick LX 2009 was no longer sold from July 2, 2010, onwards, modified versions of the device have been available for sale since.

In Canada, carrier Mobilicity began selling the device under the name "Mobiflip" and the model number PV300G in late December 2010.

In the United States, regional carrier Cincinnati Bell began selling the "Sharp Jump", model number PV300GC, in early 2011.

This modified OS is independent of any backend service, and the original Danger Web browser, Instant Messaging and Email applications have been removed.

The Mobiflip can be unlocked for voice service worldwide, but will not work for data due to the lack of an option to change the network APN.

In April 2011, T-Mobile revived the Sidekick brand for a new 4G HSPA+-compatible Android smartphone developed by Samsung, known as the Sidekick 4G, based on the Galaxy S. It incorporates features from the original series, including the keyboard, 3.2-megapixel camera (minus LED flash), and the four-button layout, and adds a new Android-powered interface incorporating elements from the Hiptop's operating system.

Each Sidekick had an IM client (with AIM, Yahoo Messenger, and MSN Messenger); an Email client with an included T-Mail account; a pre-installed game (Rockets and Rocks or Bob's Journey); an organizer with planner, a calendar, and calculator; an SMS and phone app; a Download Fun catalog (also called Catalog on Hiptop devices);[21] and later devices had a variety of social network apps accessed from a section called Communities.

Devices released in Europe also had a WAP browser (Wapaka[22]) developed by the French company Digital Airways.

A cloud service backed up all personal data like settings, planner, notes, calendar, photos and all contacts.

This will allow the installation of user-written applications to the device, but will void any software warranty provided by Danger and/or your wireless carrier.

[23] On October 2, 2009, Microsoft (the owner of Danger, Inc.) lost the ability to access user data for T-Mobile US Sidekick subscribers temporarily.

[25] Unsubstantiated reports suggest Microsoft vendor Hitachi, Danger's storage area network (SAN) provider may have had a part in the temporary data loss.

This text-based communications medium, along with on-device email and a full QWERTY keyboard, made it popular with the deaf community, providing a telecommunications tool for use both inside and outside the home.

Almost immediately it began replacing the dominant wireless devices used by the Deaf at that time, namely the Motorola T-900, PageWriter, and TimePort, as well as the early RIM and BlackBerry e-mail pagers manufactured by Research In Motion.

Lormar Logic enhanced the TDD/Relay Operator system in August 2003 by developing a means for the deaf to place calls through AOL Instant Messenger.

Access to direct TDD and relay operator communications has allowed the Hiptop/T-Mobile Sidekick and similar devices to, in many cases, replace the use of standard TDD machines, and its dominance is clearly illustrated by the evolution of its own sign in American Sign Language, made using both hands to mimic the opening of the rotating screen.

T-Mobile's decision to offer a "data only" wireless plan, thereby eliminating charges for unusable voice minutes, also played a role in the device's dominance in the deaf community.

Additionally, some local deaf non-profit groups in the U.S. will either pay all or part of the cost of the device/monthly service fees for the user to keep them "connected".