Cheap Mobile to Mobile Call from KSA to Austrailia

If you both have iPhones make sure you have data bundle and use Skype or better still viber if you are both on iPhones without FaceTime.

It's a simple 2 step thing :-
1. Buy a sim card of a provider with GPRS/Edge - I have got a zain costing 35 Riyals for 2GB data usage.
2. Buy calling credit / subscription with any of the VOIP service providers like SKYPE , Viber , FreeCall , Nymgo etc. Though keep in mind the clarity / drop rate can be frustrating with some unstable providers. Connectivity wise & Clarity wise Skype I found is best.

Agreed use skype to viber. On stc ive spent like sr40 for 15 minutes... I shouldve just found the nearest starbucks instead

I have used Nymgo and it is good for VOIP calls from smart phone