In 1971, while he was working with Boeing in Huntsville, Alabama, Paraskevakos demonstrated a transmitter and receiver that provided additional ways to communicate with remote equipment.

This formed the original basis for what is now known as caller ID.

The rise of i-mode helped NTT Do Co Mo accumulate an estimated 40 million subscribers by the end of 2001. started to adopt devices based on Microsoft's Windows Mobile, and then Black Berry smartphones from Research In Motion. and Japan, Nokia was seeing success with its smartphones based on Symbian, originally developed by Psion for their personal organisers, and it was the most popular smartphone OS in Europe during the middle to late 2000s.

They integrate and now largely fulfill most people's needs for a telephone, digital camera and video camera, GPS navigation, a media player, clock, news, calculator, web browsing, handheld video games, flashlight, compass, an address book, a note-taking application, digital messaging, an event calendar, etc.

Typical smartphones will include one or more of the following sensors: magnetometer, proximity sensor, barometer, gyroscope or accelerometer.

In the mid-late 1990s, many people who had mobile phones carried a separate dedicated PDA device, running early versions of operating systems such as Palm OS, Newton OS, Symbian or Windows CE/Pocket PC.

These operating systems would later evolve into early mobile operating systems.

The trend at the time, however, that manufacturers competed on in both mobile phones and PDAs was to make devices smaller and slimmer.

The bulk of these smartphones combined with their high cost and expensive data plans, plus other drawbacks such as expansion limitations and decreased battery life compared to separate standalone devices, generally limited their popularity to "early adopters" and business users who needed portable connectivity.

The first caller ID equipment was installed at Peoples' Telephone Company in Leesburg, Alabama and was demonstrated to several telephone companies.

The original and historic working models are still in the possession of Paraskevakos.

Before 2007, it was common for smartphones to have a physical numeric keypad or QWERTY keyboard in either a candybar or sliding form factor. introduced the i Phone, the first smartphone to use a capacitive multi-touch interface.

but it was not a smartphone, and its screen was not multi-touch.) The i Phone was notable for abandoning the use of a stylus, keyboard, or keypad typical for smartphones at the time, in favor of a large touchscreen for direct finger input as its main means of interaction.

Unlike future generations of wireless services, NTT Do Co Mo's i-mode used c HTML, a language which restricted some aspects of traditional HTML in favor of increasing data speed for the devices.