The Optus My Prepaid Ultimate plan now allows customers to roll over a maximum of 15GB of unused data by recharging before their credit expires. The previous limit was 10GB.

For a limited period, customers can also get more data for their money as well as being able to roll more of it over. Until 1 May 2016, My Prepaid Ultimate recharges come with bonus data.

$30 recharges get 1.5GB extra, $40 4GB extra, and $50 and over recharges include 3GB of bonus data.

For comparison, an extra 1.5GB of data normally costs $10 but expires in 14 days unless rolled over.

And the My Prepaid Ultimate offers aren't all about the data.

Recharges of $40 or more include unlimited (subject to the company's "fair go policy") standard international calls to China, Hong Kong, India, Malaysia, New Zealand, Singapore, South Korea, Thailand, USA and UK.

This part of the offer also runs until 1 May.