Starting today, Vodafone is offering a six month Stan subscription to new and upgrading customers who sign up to a $70 or $80 Red plan for 12 or 24 months.

If they choose the $100 Red plan instead, the free Stan subscription is extended to 12 months.

Although not made clear in Vodafone's announcement, the company's web site indicates that the Stan subscription is an alternative to the existing Spotify and Fairfax newspaper subscription offers for new and upgrading customers, not an additional benefit.

For once, existing customers don't miss out completely. As long as they are "eligible" (and the only factors Vodafone mentioned was that they must be aged at least 18, and that month-to-month SIM-only plans aren't included), they will receive a free three month subscription. Those people will be contacted by Vodafone during April.

Stan normally offers a 30 day trial period, so this seems to be a genuine promotion.

There are a couple of things to watch out for. Firstly, it's up to the subscriber to cancel the Stan subscription by the end of the trial period to avoid being charged for subsequent months.

Secondly, Stan chews up a lot of data: up to 1.13GB per hour for SD, 2.89GB for HD, or 0.57GB for a reduced quality stream for phones and tablets. So the 3GB per month included with the $70 Red plan won't go very far, and excess data costs $10 per 1GB.

That's not a problem if you're still in the first two months of a Red plan due to the unlimited 'Data Workout' period, but after that you'd need to sure that you wanted to watch that movie while riding home on the train. If you were to watch for half an hour a day while commuting, that's over 5GB a month gone before you do anything else with your phone or tablet.

However, the complementary Stan subscription can be used with any internet connection (as long as it's fast enough), and the mobile app (available for iOS and Android) automatically advises the use of Wi-Fi rather than mobile data.

"We are excited to bring Vodafone Red customers a three month subscription to the biggest deal in entertainment, and it's on us," said Vodafone general manager of postpaid Stephen Smyth.

"With the biggest library of content on an SVOD platform in Australia, and an exciting line-up of exclusive new shows, Stan is inviting Australians to discover new, exciting content.

"We've all had experience where we have turned on the TV and watched reruns of the same movie or TV show because there was nothing else on.

"Stan brings Australians choice in entertainment and together with Vodafone, we're delivering this possibility to millions of customers to enjoy on their mobile devices."

Stan CEO Mike Sneesby, said, "We are thrilled to be Vodafone's exclusive SVOD partner in Australia.

"They are global leaders in providing premium content for mobile customers and it's exciting to be part of Vodafone's entertainment offering in this market.

"With Stan, Vodafone customers can now enjoy access to the largest catalogue of TV shows and movies on an SVOD service in Australia, with new content added every day."

According to Sneesby, Stan is already streaming more than one million hours of content a month.