In the first 10 days after Apple opened its App Store for the iPhone, consumers downloaded more than 25 million applications, ranging from games like Super Monkey Ball to tools like New York City subway maps. It was nothing short of revolutionary, not only because the number was so high but also because iPhone users could do it at all.

Consumers have long been frustrated with how much control carriers - AT&T, Verizon Wireless, Sprint and the like - have exerted over what they could download to their mobile phones. But in the last nine months, carriers, software developers and cellphone makers have embraced a new attitude of openness toward consumers.

Verizon Wireless, which said in November that it would open its network to any device maker that could create a mobile phone compatible with its network, has already welcomed a few business-oriented devices. It hopes to announce new consumer phones in the coming months. When the world’s largest cellphone maker, Nokia, recently took full ownership of Symbian, which owns a popular mobile operating system, it agreed to share the software with other phone makers.

And on Monday, the LiMo Foundation, an alliance of companies promoting a rival operating system open to makers of all wireless devices, is announcing that seven new mobile phones would use that system, bringing the number to 21.

AT&T, like Verizon, has followed suit with a promise to also open its networks.

But the pressure on AT&T is also coming from another direction: Apple, its iPhone partner. AT&T has no control over the applications downloaded to the iPhones, which AT&T offers exclusively. But the proliferation of new applications and the realization that they only make cellphones more popular has convinced executives there that they need to give consumers more freedom.

The industry, of course, has selfish reasons for promoting openness. Applications spur the use of higher-priced wireless data plans and the purchase of more expensive smartphones. “What is most important for us is to have a customer sign up for a plan," said Ralph de la Vega, who is in charge of AT&T’s wireless unit. “We think we can have multiple ways to make money.”

Silicon Valley’s venture capitalists are already salivating over the enthusiasm for cellphone applications. Their investments in this category rose 90 percent in the first half of 2008, to $383 million, from the second half of 2007, according to Rutberg & Company, a technology research firm based in San Francisco.

Analysts and industry executives agree that Apple, a new entrant to the cellphone market, deserves credit for spurring the carriers and cellphone makers to change.

But there is something bigger at play, too. The market for smartphones, which are really handheld computers, has quickly expanded beyond business users. They have gone mainstream, with teenagers and women finding novel uses for them - texting snippets of their lives to friends or tracking friends on maps. The carriers and the handset makers realize they have to make the phones adaptable to those new customers.

“What is happening is inevitable,” said Walter Piecyk, a communications analyst at the research firm Pali Research who studies the mobile phone market. “Companies can’t really stop it. They might as well embrace it. Consumers are demanding these types of devices, which is good for everyone.”