Microsoft is taking a swipe at Apple by comparing its digital voice assistant Cortana with iPhone 5S' Siri.

Microsoft is at it again. After a humiliating "Scroogled" campaign against Google back in the days, the Redmond-based software company is targeting the mobile tech leader Apple. The latest advert by Microsoft compares Cortana running on a Nokia Lumia 635 against Siri on an iPhone 5S.

Firstly, comparing the low-end Lumia 635 against Apple's iPhone 5S is seen as a way to mock the difference in performance. Secondly, the responsive Cortana outperforms Siri in useful ways. The 30-second advert starts with a user asking the digital assistant to help him remind to wish his wife "Happy Anniversary" the next time she calls. While Cortana obliges with the request Siri fails to assist.

The advert continues as the user adds, "Oh, and remind me to get roses when I'm near a flower shop." Unsurprisingly, Cortana complies with user's request and Siri fails yet again. Towards the end of the ad, Cortana automatically gives a traffic update, prompting to leave before the traffic delays.

"Now that is a smartphone," admits Siri as the comparison ends.

This isn't the first time Microsoft has mocked its rivals to promote its products. Last year in December, the software giant compared its Surface 2 tablet against Samsung Galaxy Tab 3. The adverts showed the use of USB ports and its Windows OS. The company also ran down its rival Apple's iPad Air in a commercial to promote its Surface 2. Microsoft offered $200 gift cards if iPad users traded in their devices for a new Surface RT, Pro or any other Microsoft-branded product.

Watch the Microsoft ad titled "Siri vs. Cortana - Happy Anniversary," embedded from YouTube.