Asterisk simple trouble

I already install Asterisk 1.2 for Centos 5, I know is running because I use this command:
asterisk -g
asterisk
Response:Asterisk already running on…

Now, Im using the Xlite and I know the sip configuration is well done.
Im using this configuration on my Asterisk server:

sip.conf

[general]
bindport=5060

[3000]
type = friend
context=default
username = 3000
callerid=Isaac <3000>
host = dynamic
canreinvite=no
dtmfmode=rfc2833
mailbox = 3000
disallow=all
allow=ulaw
allow=g729
secret=3000
nat=yes

[3001]
type = friend
context=default
username = 3001
callerid=Portatil <3001>
host = dynamic
canreinvite=no
dtmfmode=rfc2833
mailbox = 3001
disallow=all
allow=ulaw
allow=g729
secret=3001
nat=yes

extensions.conf

default]
exten => 3000,1,Dial(SIP/3000,30,Ttm)
exten => 3000,2,Playback(invalid)
exten => 3000,3,Hangup
exten => 3000,102,Voicemail(u3000)
exten => 3000,103,Hangup

exten => 3001,1,Dial(SIP/3001,30,Ttm)
exten => 3001,2,Playback(invalid)
exten => 3001,3,Hangup
exten => 3001,102,Voicemail(u3001)
exten => 3001,103,Hangup

exten => 3002,1,Dial(SIP/3002,30,Ttm)
exten => 3002,2,Playback(invalid)
exten => 3002,3,Hangup
exten => 3002,102,Voicemail(u3002)
exten => 3002,103,Hangup

Im dont getting any response in the CLI (asterisk -rvvv)
Do I need to modify some other files to have two softphone working or Im missing something?