Not for everyone, but CrazyTel have a deal they’ve been promoting on whirlpool.
Basically, on the PAYG plan it’s free to use and $1/month for a landline number which is forwarded to your smartphone. This can be setup to go to voicemail. The recorded voicemail messages are then emailed to your associated email address as *.wav files so you can return them when you’re ready from your personal mobile (with presumably free calls).
Call forwarding costs to Australian mobiles 0.05c/min and 0.02/min to other landlines. Personally, the straight to voicemail (professional voice actor to record one ~ $30 off Fiverr) > voicemail message sent to email monitored by workplace > free call from mobile is, in my opinion, the ozbargain power move.
Good for businesses who are after a landline to boost credibility without having to worry about the costs and inconvenience of running two phone numbers/lines.
Hope it’s handy to someone :)
Only the cost of your data, if you're using mobile data. I read that the data usage is about a gigabyte an hour, but that information is probably outdated by now.