Hi, For New Zealand. Nice and simple is NZ.
The Spark network uses both (HSDPA/UMTS) 2100mhz and 850mhz depending on your location. 4G does indeed operate on 1900mhz. Within city centres the network operates on 2100mhz and outside of the city centres its 850 mhz, these are both 3G frequencies. 4G only operates in certain places. From the link you sent me for the modems, it looks like the PLS8-E will not pick up our 850mhz frequency, which could cause problems depending on your location. If you want to guarantee coverage, it may be better to go for the PHS8-P/J/K or PXS8. Usually we cannot recommend individual devices, especially modems as these are devices we do not usually support. However, your best bet is with PHS8-P/J/K or PXS8. However, after looking at your coverage, if you feel you can get by with the PLS8-E device that could also work, but please be aware, it will not work outside of city centres due to not being able to pick up the 850mhz frequency.