Pairing phone to Satnav

[zipdip]

Hi
I took on the job of getting a old guys birthday present a chinese sat nav working had to download the maps onto my laptop then onto his sat nav took me some time but did it and it works fine,now for the easy bit pairing his phone,with both searching nothing,I tried my Iphone it paired straight away,he has a Doro flip phone with the large buttons which I have paired with a parrot the guy had a little while ago,I thought bluetooth was the same on all things,anybody got any ideas