subscription-manager register network error unable to connect to server error: [Errno 110] Connection timed out

Hello,

Rhel 6.3 server trying to register with RHN network. All required port and hosts open from firewall as per document https://access.redhat.com/solutions/10818

Ping & telnet to rhn also working fine.
telnet xmlrpc.rhn.redhat.com 443 >>> connecting
telnet xmlrpc.rhn.redhat.com 80 >>> connecting

subscription-manager register --username xxxxxxx --password xxxxx
Network error, unable to connect to server.
Please see /var/log/rhsm/rhsm.log for more information.

Logs file error as below:
15-12-28 10:37:57,124 [INFO] @connection.py:495 - Connection Built: host: subscription.rhn.redhat.com, port: 443, handler: /subscription
2015-12-28 10:38:11,476 [INFO] @connection.py:473 - Using basic authentication as: furqanalam
2015-12-28 10:38:11,477 [INFO] @connection.py:495 - Connection Built: host: subscription.rhn.redhat.com, port: 443, handler: /subscription
2015-12-28 10:38:11,477 [INFO] @managercli.py:777 - Registering as existing consumer: a8da4e4d-1ac5-48e8-a42e-f1f1e83875ec
2015-12-28 10:38:11,478 [DEBUG] @connection.py:306 - Loading CA PEM certificates from: /etc/rhsm/ca/
2015-12-28 10:38:11,478 [DEBUG] @connection.py:288 - Loading CA certificate: '/etc/rhsm/ca/candlepin-stage.pem'
2015-12-28 10:38:11,479 [DEBUG] @connection.py:288 - Loading CA certificate: '/etc/rhsm/ca/redhat-uep.pem'
2015-12-28 10:38:11,479 [DEBUG] @connection.py:327 - Making request: GET /subscription/consumers/a8da4e4d-1ac5-48e8-a42e-f1f1e83875ec
2015-12-28 10:39:14,592 [ERROR] @managercli.py:101 - Error during registration: [Errno 110] Connection timed out
2015-12-28 10:39:14,592 [ERROR] @managercli.py:102 - [Errno 110] Connection timed out

Anyhelp how to fix this issue and connect to RHN network.

Regards,