Amaysim Unlimited Post Paid SIM includes unlimited standard calls and text and 4GB of data, making this plan ideal for heavy users, who use their phone every day, make 100-200 calls, send 100 text messages and use around 2GB of data each month. This plan is on a 30-day contract with handsets available for purchase or you can BYO. Amaysim is shaking up the Australian mobile market with cheap call rates, no flagfall, and Australia-based customer service.