If the clients are happy to talk on Skype then there will only be the cost of the internet. If you are calling to mobile, land lines then there is a cost, but quite reasonable and you can also get an unlimited package.
If you do video chats, Skype is also fine. Zoom is another company which seems to be popular for video chat (not sure of the cost though).
You can also set up Australian 03/02/1300/1800 numbers also and answer them on your mobile laptop.
harryopal wroteIf I am calling someone and have go through a switchboard I always say I am calling from Indonesia and that prepares them for any quality issues and tends to make the telephone answering people put you through without too much delay.
Yeah, I used to have to do that also as sometimes there was quite a delay, especially pre-fibre days. Quality has improved tremendously. The person you are speaking to in a call centre in Australia these days, could also be located anywhere in the world and they are also probably using an IP phone system.
If you are doing this thing all the time, you can get a good/almost trouble free set up going.