connecting 2 routers and 2 network segments

I've got 2 networks:
192.168.1.0
192.168.15.0
And 2 routers:
Linksys WRT54G Call it Router A
Linksys WRTP54g (a vonage supplied router) Router B
ignore the wireless aspect of this, the vonage routers wireless is
disabled due to voice quality issues when mixed with other traffic.

Router A handles the internet
Router B handles phone and 2 NAS devices

Here's my layout:
Internet--> WAN port <-> RouterA <-> Lan side ports >--> PC
-> Lan side ports >--> PC
-> Lan side ports >--> Router B WAN
Router B Lan Port-> NAS 1
Router B Lan Port-> NAS 2
Router B phone Port-> Phone

PC's connected to router A work great
Phone works ok

I cant talk to the NAS's from a PC on router A. e.g cant talk to router B
from router A
Can someone tell me the basic setup to get this working? I've experimented a
bit but havnt got it to work. With a switch type setup and one network of
192.168.1.0 i can talk to the NAS's but the phone doesnt work so I really
need to have Router B on a different subnet with its WAN port connected to
a LAN port on router A
Thanks
Eric