OK so I have a business and I am wanting to setup a voicemail / message taking service

• I have a skype number for the business which I can redirect or migrate to somewhere
• Also have a mobile number on 2D which also needs to be redirected
• Most answering services cost around $250 / month + $1 per text

I have found this service from Spark for only $12 - $49 per month

https://www.spark.co.nz/business/shop/mobile/plansandpricing/mobilepa.html

I am on a prepay $19 plan on 2Degrees, and thought if I setup a magic number ($6 for 500 mins) to redirect to a prepay sim from Spark or to a DDI (I assume this is only for a mobile plan, in fact it probably is only for a non prepay plan?).

I thought I can setup a redirection on no answer from my phone Samsung Galaxy 6 and then just have to make sure that its fully charged all the time.

Are there any other ways to do this? Also can I redirect the text from the Spark number?  
I dont really want to move off 2D but they don't have a service like this. Neither do Voda.

Haven't found any other call centre that is anywhere close in price, but it sort of is getting pretty complex with the redirection options..