Peoblem with basic Basic asterisk configuration

Hi,
I am new to asterisk and even linux also . I have downloaded thew asterisk 1.4 and successfullt compile it. I also configure 2 xlite phone with asterisk and make call between them. Now i want to register with my sip provider and make outbound call my sip provider is gafachi. I have done configuration in sip.conf :

register => username:password@@64.192.112.13

[gafachi]
type=friend
username=username
secret=password
host=username.sip.gafachi.com
canreinvite=no
fromuser=username
dtmfmode=rfc2833
context=gafachi-incoming

when i reload the file i get information on cli as :

[Aug 9 17:16:27] NOTICE[7317]: chan_sip.c:7217 sip_reregister: – Re-registration for a2541shRzJKLjtQA@64.192.112.13
REGISTER 12 headers, 0 lines
Reliably Transmitting (no NAT) to 64.192.112.13:5060:
REGISTER sip:64.192.112.13 SIP/2.0
Via: SIP/2.0/UDP 192.168.96.57:5065;branch=z9hG4bK3c05c3ba;rport
From: sip:a2541shRzJKLjtQA@64.192.112.13;tag=as230fb985
To: sip:a2541shRzJKLjtQA@64.192.112.13
Call-ID: 13ad59d804be50ab74fb364d0c1d71df@192.168.96.57
CSeq: 102 REGISTER
User-Agent: Asterisk PBX
Max-Forwards: 70
Expires: 3600
Contact: sip:s@192.168.96.57:5065
Event: registration
Content-Length: 0


localhost*CLI>
<— SIP read from 64.192.112.13:5060 —>
SIP/2.0 200 OK
Via: SIP/2.0/UDP 192.168.96.57:5065;branch=z9hG4bK3c05c3ba;received=59.95.152.178;rport=5065
From: sip:a2541shRzJKLjtQA@64.192.112.13;tag=as230fb985
To: sip:a2541shRzJKLjtQA@64.192.112.13;tag=gss5f72d876bc216f8b77109d9464a5a426Call-ID: 13ad59d804be50ab74fb364d0c1d71df@192.168.96.57
CSeq: 102 REGISTER
Server: Gafachi UAS v110.05
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE
Contact: sip:s@192.168.96.57:5065
Date: Thu, 09 Aug 2007 11:45:49 GMT
Content-Length: 0

<------------->
— (11 headers 0 lines) —
Scheduling destruction of SIP dialog ‘13ad59d804be50ab74fb364d0c1d71df@192.168.96.57’ in 32000 ms (Method: REGISTER)
[Aug 9 17:16:29] NOTICE[7317]: chan_sip.c:12212 handle_response_register: Outbound Registration: Expiry for 64.192.112.13 is 3600 sec (Scheduling reregistration in 3585 s)
localhost*CLI>
<— SIP read from 192.168.96.60:5065 —>

<------------->
— (0 headers 1 lines) —
Really destroying SIP dialog ‘13ad59d804be50ab74fb364d0c1d71df@192.168.96.57’ Method: REGISTER
localhost*CLI>
<— SIP read from 192.168.96.60:5065 —>

when i trace this with ethereal i found that registration request go to 64.192.112.13 but no response return from there.
What is the reason please help me :

Yogesh