Problem of invalid extension?

Asterisk Asterisk Support
1

i have two servers both having x100P cards( single channel ). i have added following statments. after installing the sample conf files.

iax.conf

[lhrserver]
type=friend
host=dynamic
regexten=2001
user=lhrserver
secret=alpha
context=default

register => isbserver:alpha@192.168.0.20

[demo] ( its by default in the iax.conf )
type=peer
username=asterisk
secret=supersecret
host=216.207.245.47

on the other server same config is written with the name of isbserver and registerd it as in this

extensions.conf

[demo]
exten => s,1,Answer
exten => s,2,Wait,2
exten => _011429X.,3,Dial(${TRUNK}/${EXTEN:${TRUNKMSD}})
exten => _011429X.,4,Congestion
exten => s,5,Wait,2
exten => s,6,Hangup

[default]

include => demo

now when i call to the server it answers but when i enter extension it gives the error of invalid extension i.e 0 or any other which we write after _ . and the fone is hunup.

i will be thankful to u for this help

2

why is this so 6 people has gone through the post and not the single one has replied to it. i dont think this is very difficult question, especially for people here.
i have gone through the documentation of asterisk and the information on voip-info.org. but there is still problem.