Connecting two boxes togather

What I am trying to do is have incoming calls to go to box2 from box1.

I set an IAX2 ext in box1 and was able to dial out on the extension from box2

I set a trunk in box2 but when I tell the inbound call to go to that extension it just rings for a bit and then stops?

outbound calling works just fine.

how would I solve this issue and can I have an asterisk boxes as a IAX2 extension ?

box1 (incoming)
FreePBX 2.5.1.5
Asterisk (Ver. 1.4.23.1)

box2 (extension)
FreePBX 2.4.1.0
Asterisk (Ver. 1.4.21.2):

box 2 peer details

host=box1-ip
trunk=yes
user=box1-extension_IAX2_EXT
secret=box1-password_for_IAX2_EXT
allow=ulaw
type=friend
context=from-pstn
insecure=very
dtmfmode=rfc2833