There was a post above about Vodafone. Perhaps not off topic because it deals with the underlying question : how to make cheap calls back home.
And "Yes" they have some service disappointments ... but there is not a Telco alive that hasn't disappointed me in some way or other. (pun intended)
Vodafone has a series of "Red Sim" plans with sims only in the nano size. (but you can overcome that with an adapter for $2) These plans are available sim only; month to month; 12mo, 24 mo, or with a phone. Varying levels of data ... the sweet spot for me was $45 for unlimited calls, texts, texts to OS 3gb data AND 300 minutes (yep 5 hours) on international calls from Australia. Handy for pre travel calls …
The plan also allows you to pay an extra $5 / day to use the same services (calls, sms, data) in any of 47 countries. I think you need to pre book the days. By contrast Optus has a different set of countries , calls only, and a skinny data allowance for $10 / day.
I could no see any such sweet deal from Telstra. Perhaps others are aware of one?
So one sweet plan is to move to Vodafone for one month only, for a single OS vacation .. then move back to your preferred carrier. OR, even take out a new monthly contract just for the vacation and the pre planning time ( to call hotels etc from AU) . Put that Red sim in an old phone and you have full travel communications in a phone you don’t mind being stolen … Leave your good phone turned on (yet hidden from theft) to see who is calling, don’t answer it… but call them back on your travel phone.
The super sweet deal for the frequent international traveler is the Vodafone $100 red sim plan. It looks like you need to sign up for this one and take a phone for 24 months; however it includes infinite calls, texts in Australia and OS, and the 300 minutes of OS calls and 6gb of data. But the real sweetener is that it includes the $5 roaming fee. That's all the calls and 6gb data WHILE OS. Assuming the 47 countries listed suit your travel plans that caps your annual costs at $1200 p.a. and gives you a new phone. For some Frequent Flyers that would be a stunning deal.
The devil is often in the detail, but on my reading it seems very fair. For example if you are in one of the 47 countries, and call Australia its included. if you call a 3rd country the call comes out of your 300 minutes call allowance, as if you were in Australia. Very Fair!
Gary
PS I’m not a Vodafone employee. I dropped Vodafone as my carrier following a series of disputes last year but not over call issues - only accounting matters. My advice is you should take this deal if it suits, sign up with a direct debit authority to a cheque account, rather than a credit card... and then that allows you to cancel the direct debit authority with your bank. Then of course pay the account on time. With 20:20 hindsight that would have insulated me from their accounting errors.