Modems and third party routers

[StriderX]

Probably a stupid question, but is the BT openworld(reach) modem the only one that works with the master socket?

Every guide on the internet (wrt the UK) seems to use it, can you not use any third party modem?

 

[StriderX]

I see, well if i were to go for one (and this is probably pointless to ask), but there are two types of power supply looking at Ebay, does it matter if its the black one or the white one?