On Server A, iax_additional.conf:

[linux77]
type=user
auth=md5
secret=linux77
context=from-internal

On Server B, in iax.conf in the "general" context:
register => linux77:linux77@linux40

On Server B, in iax.conf at the end of the file:

[linux40]
type=peer
host=linux40 (or "dynamic" which would then require a "register" command by the peer.)
auth=md5
secret=linux77                  ; redundant when already embedded in Dial string
username=linux77       ; redundant when already embedded in Dial string

On Server B, in extensions.conf:

exten => 1237,1,NoOp( exten 1237 )
exten => 1237,2,Dial(IAX2/linux77:linux77@linux40/103,30,r)
exten => 1237,3,NoOp( call to .40 failed )
exten => 1237,4,Congestion

What I expect to happen:
I dial 1237 on a SIP phone that is attached to Server B (and otherwise works) and it would connect to Server A nad dile the extension 103

What happens:

Nothing -- I don't even get the NoOp's from the 1237 exension.

Server B was installed with asterisk today and the config files were generated with "make sample" and then editted.  Server A is our "production" server that has been operating fine for a while.

From the register line, I see this error on the *CLI> on Server B:

May  3 17:19:59 NOTICE[4784]: chan_iax2.c:7742 socket_process: Registration of 'linux77' rejected: 'Registration Refused' from: '192.168.1.40'

and this on Server A:

May  3 17:22:26 NOTICE[18634] chan_iax2.c: No registration for peer 'linux77' (from 192.168.1.77)

I have been working from the examples on this page:

http://www.voip-info.org/wiki/view/Asterisk+-+dual+servers