Siri, Apple's intelligent personal assistant and 'knowledge navigator,' is designed to make iPhone users' lives easier. But it appears, however, that Siri is a lot more helpful to those who have signed up for certain Apple services. One example of this is Siri's refusal to provide music information to those people who aren't subscribers to Apple Music.

Several Siri users who aren't paid members of Apple's streaming service, including Pandora co-creator Tom Conrad, have noticed her less-than-helpful attitude when it comes to chart enquires. "I can't look up the music charts for you. You don't seem to be subscribed to Apple Music," is a typical answer non-subscribers can expect.

As many Apple music listeners are coming to the end of their three-month free trials, this looks like a move by the company to try and coax them into taking out full subscriptions - of course they could just use Google to answer their music queries.

It has been pointed out that Siri gets its music information from Apple's streaming service, and directs users with music questions into the iOS app. But there's no reason why non-subscribers can't be directed to a typical web search.

It's not as if Apple desperately needs to attract more paying subscribers to Apple music; last week, company CEO Tim Cook revealed the streaming service reached 6.5 million paid subscribers within the first month after the end of the free trial period for early adopters. It may be lagging behind Spotify's 20 million paid subscribers, but Apple Music is on its way to becoming a billion dollar business.

Apple has not commented on the story.