Connect Two Asterisk Servers Using IAX2

Two Asterisk servers are connected by IAX2 trunking. All dialing numbers started with "3" will be forwarded to the other server with the first digit stripped.

Server A's IP is "192.168.0.33"
Server B's IP is "192.168.0.66"

Server A - iax.conf
[server-b]
type=peer
host=192.168.0.66
username=server-a
secret=server-a-pass
disallow=all
allow=ulaw

[server-b]
type=user
secret=server-b-pass
disallow=all
allow=ulaw
context=internal

Server A - extensions.conf
exten => _3.,n,Dial(IAX2/server-b/${EXTEN:1})

Server B - iax.conf
[server-a]
type=peer
host=192.168.0.33
username=server-b
secret=server-b-pass
disallow=all
allow=ulaw

[server-a]
type=user
secret=server-a-pass
disallow=all
allow=ulaw
context=internal

Server B - extensions.conf
exten => _3.,n,Dial(IAX2/server-a/${EXTEN:1})

References:
http://www.syednetworks.com/connection-between-two-asterisk-servers-using-iax#more-87