The mobile industry is one of the world's largest.

Billions of people the world over now own a smartphone -- and it doesn't look like it will stop anytime soon. Hundreds of companies are working in unison to provide handsets, software, chips, and services.

Below are the 10 largest companies operating in the industry by market cap. Although there are larger companies that compete in the wireless market in some capacity (such as Microsoft and Intel), the list includes only firms whose primary business centers on mobile.

10. Deutsche Telekom $84 billion
Deutsche Telekom (NASDAQOTH: DTEGY) is one of the largest providers of mobile phone services in Europe, particularly in its home market of Germany. It also owns the majority of its once wholly-owned U.S. subsidiary T-Mobile.

9. Vodafone $90 billion
Another telecom giant, like Deutsche Telekom, Vodafone (VOD) is one of the largest providers of mobile phone services in Europe. It has about one-third of the German and Spanish markets, and one-quarter of the U.K. market.

8. Qualcomm $114 billion
Chipmaker Qualcomm (QCOM -1.75%) provides the processors that power many of the world's smartphones, including most of the Android-based handsets sold in the United States. Its Snapdragon series has been the standard Android processor for roughly the last five years. Its latest model, the Snapdragon 810, is expected to power most of the flagship Android handsets sold this year.

7. Samsung Electronics $167 billion
Korean giant Samsung (NASDAQOTH: SSNLF) has seen its market share fall in recent quarters, but it remains the world's largest producer of smartphones. It competes in almost every segment of the handset market, and in almost every country. In addition to its own handsets, Samsung also produces components for many other handset vendors.

6. AT&T $170 billion
Ma Bell is one of the largest providers of mobile phone service in the United States. AT&T (T 1.30%) was the first carrier to offer the iPhone, and 94% of its customers purchased a smartphone last quarter. Seeking growth, it has begun expanding into international markets, including Mexico.

5. Verizon $204 billion
Verizon (VZ 0.88%) is the largest wireless provider in the United States. Verizon was ahead of its rivals in pushing 4G LTE connections, and its current network is often considered to be the best in the nation.

4. Facebook $234 billion
Some may object to the inclusion of Facebook (META 1.54%) on this list. The company is a social networking giant -- it doesn't offer wireless service, manufacture handsets, or sell mobile chips. Yet I believe Facebook should be considered the third largest company in the mobile industry.

Facebook owns many of the most popular mobile apps: not just its namesake social network, but also Instagram, Messenger, and WhatsApp. Collectively, these apps touch billions of mobile phone users on a daily basis. Facebook derives roughly two-thirds of its revenue from mobile advertising, and the company's future appears inextricably tied to the mobile industry, with its latest initiatives -- including its attempt to turn Messenger into an app platform -- aimed squarely at mobile.

3. China Mobile $292 billion
China Mobile (CHLK.F)
(CHLK.F)(CHLK.F) is the dominant mobile phone provider in China, and the single largest provider of mobile phone service in the entire world, with just over 800 million subscribers. China Mobile's network covers the majority of mainland China, but is relatively undeveloped -- 4G-capable handsets are owned by a minority of its customer base.

2. Google $367 billion
In contrast to Facebook, most of Google's (GOOG 0.37%) (GOOGL 0.35%) current revenue is likely still coming from the desktop (unfortunately, it does not disclose an exact figure). Yet, it would be strange to exclude Google from this list.

It's operating system, Android, powers the overwhelming majority of the world's mobile devices, including about 80% of smartphones. Google's services -- including Maps, gmail, search, and YouTube -- are among the most popular on mobile platforms.

1. Apple $735 billion
Not only the largest company in mobile, Apple is the largest company in the world. The iPhone, which continues to generate the bulk of Apple's revenue, created the modern smartphone industry, establishing the concept of a mobile app and fueling the demand for robust and speedy wireless connections. Apple doesn't sell the most phones, but it tends to attract the most valuable buyers, and enjoys strong consumer loyalty.