I've been asked to help with a new phone in an area that has between 0-2 bars reception for Spark & Vodafone networks.  

I really like the Vodafone femtocell, but in this instance it's not practical, as reception is needed over the whole farm if possible.  Plus, these people are with Telecom (if Vodafone had a solution however......).  I believe telecom does have better reception where this farm is.

My question is this:  Is there any phone (on any network) that priorities good reception above everything else?  Is there a list of phoes with best reception?  Telstra Ausralia shows the Galaxy S5 and the Xperia z2 mini as being best for rural areas.  Is that true for NZ cell frequencies?

I see some places sell cellphone repeaters.  Can these be installed with an areal at each of the main farm sheds?  Are they legal in NZ? are they effective?

Cheers!