I have the following architecture - SIP provider <-> Kamailio <-> Asterisk servers

I currently do not have any issues connecting my asterisk servers to Kamailio server. I am however having issues connecting my Kamailio server to my SIP provider. I am using the uac module for registration and have stored my credentials in the uacreg table. When I sniff on my network, I am able to see Register message being send out and receives an OK from my provider. But I am still unable to get incoming messages to Kamailio. Also these SIP responses from the SIP provider do not make it to kamailio route as I have logged any message that enter the request_route.

SIP Messages from Wireshark - 

1) 19 563.919267 10.67.XXX.XXX 10.232.XXX.XXX SIP 497 Request: REGISTER         sip:ims.airtel.in  (1 binding) | 

2) 20 564.040917 10.232.XXX.XXX 10.67.XXX.XXX SIP 480 Status: 401 Unauthorized | 

3) 21 564.041574 10.67.XXX.XXX 10.232.XXX.XXX SIP 744 Request: REGISTER sip:ims.airtel.in  (1 binding) | 

4) 22 564.173338 10.232.XXX.XXX 10.67.XXX.XXX SIP 649 Status: 200 OK  (1 binding) | 

Here 10.232.XXX.XXX is my SIP providers proxy address and 10.67.XXX.XXX is my local IP of the lan connected to the SIP line.