There's no "$20 month to month mobile phone service". In this case, the minimum spending should $38($20 + $18). You are not an existing Vodafone customer? You can just sign up a $20 month to month mobile phone voice service and cancel it with the mobile broadband service in the next month. On top of that,some stores offer an additional 10% discount which means you are going to pay $18 instead of $20. So you guys can use whatever sim card from other network providers(Telstra, Optus or etc) after unlocking the device.
I'm 99% sure that you can unlock this 4G pocket wifi device for free on Vodafone website However, the $10/mth is excluded from this offer, so your minimum spending should be $20 Vodafone month to month mobile broadband services - $10(1GB)/mth, $20(2.5GB)/mth…
Here is a trick - if you sign up the month to month plan, you can actually cancel your mobile broadband service anytime you want(though minimum one month fee applies) and keep your 4G device. So basically, if you are an existing Vodafone customer, you are getting a free 4G Pocket Wifi device for signing up Month to Month/12 Mth/24 Mth Mobile Broadband contract with Vodafone. I'll try and sum up what the deal was without overquoting too much: Please continue to discuss the deal here. Mod: We unpublished the original deal as there was an issue with the OP posting on behalf of Vodafone.