SVI's Vodafone plan provides $5 per day roaming in selected countries. This will give you access to your Australian data and will give you unlimited calls in the country you are in and to Australia.
Please be aware if you roam in a country not on the list (eg Gulf states like Dubai, UAE, Qatar or South Korea) you will be charged $1 per MB of data.
Please see https://www.vodafone.com.au/plans/international-roaming for coverage details
This is automatically activated on your account, you do not need to do anything in advance of going overseas.