I can't seem to find any mention of costs for call forwarding / diversion on 2talk. My assumption is this means there's no cost for setting it up or per use (if you have a 2talk number that supports it i.e. a cloud PBX one). You just have to pay the cost you'll pay as if calling the number you're forwarding to from your 2talk. And I assume you only pay if pick up on the forwarded number. So if your forwarding to a local line you'll pay the local call charge. If forwarding to a NZ mobile you'll pay the NZ mobile charge etc. Does it also use your includes minutes if you have any? If it matters, I'm particularly thinking of 028 numbers but also generally (hence mention of included minutes).
Is it the same for simultaneous ring assuming you pick up on another number? Again mostly thinking of a 028 number although also thinking generally. (To be clear I mean https://help.2talk.co.nz/hc/en-gb/articles/360019242152-Simultaneous-Ring not the shared line/multiple login feature.)