SAN FRANCISCO (Reuters) - Apple Inc AAPL.O and Salesforce.com Inc CRM.N are entering a partnership in which the iPhone maker will help Salesforce build the iPhone maker's features such as its Siri voice assistant deeper into Salesforce's own mobile apps, which are widely used in the sales and marketing industries.

In exchange, Salesforce will make software tools so that the big businesses that use its back-end technology to power their own apps can build better products with features specific to iPhones and iPads.

Apple and Salesforce both have huge ecosystems of third-party software developers. About 20 million developers make software for Apple devices, most of them focused on the consumer, while Salesforce has about 5 million developers who tap into its back-end systems to build business applications - a market that Apple has been expanding into through deals with International Business Machines IBM.N, Cisco Systems CSCO.O and Accenture ACN.N.

The partnership means that a salesperson can use Siri after a customer meeting to update that customer’s record with notes from the meeting, flag a customer service issue for a support team to follow-up on and many other data-entry tasks that can eat up valuable time.

“If you look at enterprise in general, voice has not been used as much as in consumer,” Apple CEO Tim Cook told Reuters in an interview. “We’re going to be able to provide the sales rep instant access to things using your voice instead of clicks and going through different apps. We’re changing the way people work, and that’s always been at the heart of what Apple is about - changing things for the better.”

In exchange, Salesforce is building tools so companies that tap into its back-end systems can make better use of Apple-specific features like Siri.

At Salesforce’s annual customer conference this week, Marriott International will demonstrate a new system that uses Salesforce and Apple tools so that hotel guests can turn up the heat, order a sandwich or hail a ride using Siri with an Apple HomePod in their hotel room. And at the next Marriot the guest stays at, Siri will remember the guest’s preferences - even their favorite sandwich, Salesforce CEO Marc Benioff told Reuters in an interview.

“I don’t think I’ve met with a single customer in the world that doesn’t want me to help them do more with Tim’s products,” Benioff said Cook and Apple in the interview.

Salesforce also runs an educational platform called Trailhead, where it says one in four people who take courses in how to build business apps with Salesforce’s tools ends up getting a raise or promotion. As part of the deal, Apple and Salesforce will add courses on how to develop iPhone and iPad applications.

“These people are learning the tech skills that are elevating their careers,” Benioff said.