While most consumers still aren’t turning to Amazon Alexa to order a new pair of heels, voice commerce on mobile apps is on the rise.

According to a recent study conducted by audio and AI company Voysis, more than half of voice commerce is conducted on mobile phones with assistant programs like Siri or emerging platforms that are enabling audio conversions. Though use of smart speakers has increased from 26 to 39 percent in the past four months, more than 50 percent of all voice-activated sales are made on mobile phones, the report found.

This is in large part because significantly more people have mobile phones than smart speakers: Today, an estimated 79 percent of adults own smartphones compared to 21 percent that own smart speakers like Amazon Alexa and Google Home. However, the rise of mobile voice sales is also a result of retailers investing more heavily in voice-activated mobile apps and technology, according to Ryan Macinnis, director of marketing at Voysis. Now, fashion and beauty companies are starting to eye a piece of the voice retail market, which is expected to account for $40 billion in U.S. consumer spending by 2022.

In order to do so, many brands are looking to test methods of using voice to drive conversions. While some are adding retail features to voice assistant bots, like Siri and Google Assistant, others are creating their own voice-activated services in an effort to carve a competitive edge against Amazon.

One such program is JetBlack — the on-demand, subscription-based e-commerce program operated by Walmart’s retail incubator Store No. 8 — which is providing a new platform for voice commerce on mobile. While JetBlack is still in beta stage, Macinnis said it has a unique value add that might be particularly conducive to boosting the use of voice.

“For JetBlack, the unique experience is powered by a voice and chat text service that’s targeted at upper-class and working-class moms,” he said. “They’re on-the-go so much that they don’t have an access to a smart speaker. That’s where brands are starting to think about voice. That’s where we’ve seen a lot of the interest.”

Still, historically (as well as in early use cases of JetBlack) consumer packaged goods have had the most success with voice commerce, given the ease of replenishing staples and basic items. As fashion brands try to find ways to use voice, brands like H&M are experimenting with the technology in physical retail stores before using it for conversions. The fast-fashion retailer recently launched a voice-powered smart mirror that allows shoppers to verbally ask style questions in fitting rooms and get suggestions using virtual reality.

“There’s no intent to drive purchase, but they’re trying to understand what their brand identity is when it comes to voice and how they can adopt the technology,” he said.

Others, like The North Face, have identified more tangible use cases for voice commerce to drive sales of apparel. In the past few years, the company has enhanced its voice-enabled search function on both desktop and mobile, helping shoppers find what they need more quickly. On the site, users can select a microphone button and verbally request their search rather than clicking through menu pages.

Ultimately, companies are seeking ways to integrate a variety of technologies at once to improve the shopping experience, and voice has increasingly been one of them. While 20 percent of consumers have used voice shopping, other technologies like AI and VR can boost this number. Additionally, given that voice is still a new technology, experts say it will continue to take time to catch on, starting with early adopters like Gen-Z.

“Voice shopping is very new,” the Voysis report stated. “Siri has been with us since 2011, but the use of voice for the consumer shopping journey has only really emerged in the past two years. Given its short lifespan to date, it is remarkable that $1.8 billion was transacted by voice in 2017 in the U.S.”