San Francisco: As Apple prepared to open its much-awaited annual Worldwide Developers' Conference (WWDC) here on Monday, speculation was rife about the biggest announcement expected from the Cupertino, California-based tech giant: developers' access to Siri, Apple’s digital assistant. According to the Wall Street Journal (WSJ), Apple may allow iPhone users to ask Siri to call for an Uber ride or check in for a flight from an airline app. Currently, the virtual assistant is set apart from most other services in the iPhone. On the other hand, Amazon's virtual assistant Alexa has this facility where you can order a pizza or even check your credit card balance. Apple may add more core functionality into Siri using artificial intelligence (AI). Another expected update may be a Siri Software Development Kit (SDK) which will allow developers to integrate their own apps with Siri. Siri may also be coming to the Mac, a report on The Information website said. Apple is also expected to launch a virtual assistant-based speaker, something similar to Amazon's Echo and Google's Home speaker. The tech giant may also announce iMessage service for Android phones. This announcement, if it happens, will let Android and iOS users to communicate freely, reported MacDailyNews. iMessage is an iOS service which lets Apple users communicate with each other using data. To put it simply, it's like WhatsApp which works only for some of the Apple devices. The service is so far available on iPhone, iPad, and iTouch with iOS 5 or above. Mac users can also avail it if their Apple PCs run OS X Mountain Lion or above. Apple Pay is also expected to work in-browser, tapping into your stored payment information to complete online transactions. Apple is also slated to refresh its entire software lineup. Apple has four operating systems- for iPhone, iPad, Apple TV and Apple Watch and Macs, the WSJ report added.