Vodafone Prepay: $19/1GB+100min/7days in 70 Countries: UK, USA, Australia, Japan, SKorea Most of: SE Asia, SAmerica, EU, Pacific

Need to visit an Australian offshore detention centre? Well if you're with Vodafone prepay, you can post your lovely holiday snaps of Nauru for $19 a week on Vodafone's prepay add-on pack! Covering 70 countries, the $19 pack is perfect for travellers wanting to Instagram inspiring photos of random people on the street without their consent but don't want to bother with the time honoured British/American trick of repeating "I want a local SIM card" English, albeit in an increasingly slower and angrier tone to the locals for half an hour!

Roaming Packs:
* $5/day 200MB, 20 mins call, 20 txt
* $19/day 1GB, 100 mins call, 100 txt

The packs are valid in:

Australia, Anguilla, Antigua & Barbuda, Antilles, Argentina, Aruba, Austria, Barbados, Belgium, Bermuda, Brazil, British Virgin Islands, Bonaire, Bulgaria, Canada, Cayman Islands, Chile, China, Colombia, Croatia, Cyprus, Curacao, Czech Republic,
Denmark, Dominica, Estonia, Fiji, France, Germany, Ghana, Greece, Grenada, Haiti, Hungary, Hong Kong, Iceland, India, Indonesia, Ireland, Israel, Italy, Jamaica, Japan, Kosovo, Latvia, Lithuania, Liechtenstein, Luxembourg, Macau, Malta, Malaysia, Mexico, Monaco, Montserrat, Montenegro, Nauru, Netherlands, Norway, Panama, Papua New Guinea, Peru, Philippines, Poland, Portugal, Puerto Rico, Romania, Samoa, Singapore, Serbia, Slovenia, South Africa, South Korea, Spain, St Kitts & Nevis, St Lucia, St Maarten, St. Vincent & The Grenadines, Switzerland, Sweden, Thailand, Taiwan, Tonga, Tunisia, Turkey, Turks & Caicos, United Kingdom (including Jersey), Uruguay, USA, Vanuatu

It's actually quite an impressive list of destinations, covering places like Kosovo or Liechtenstein. If we're talking about Japan, SKorea, USA and Canada, roaming might be cheaper in the short term because of their pretty high upstart SIM costs. Also pretty good deal for a country hopping trip. Plus there's also the niceness of being able to keep your NZ number while overseas for business or 2FA. Spark is cheaper at $15/1GB/7 days 0 min but roams to fewer countries.