Hi CNZ, I would recommend taking a look over the Vodafone coverage map on the Vodafone NZ website as it would provide an indication as to what mobile coverage is available at the address for outdoor purposes. Also, good news is that we've released Wi-FI calling, It’s a new way to call or TXT if you can’t access our mobile network, by using Wi-Fi instead. You'll just need a voice calling enabled plan, an eligible phone and a good quality Wi-Fi connection. For more information on Wi-Fi calling you can check this out via the Vodafone NZ website. 

Thanks, Jovi from VFNZ.