***** The value that you've specified on the option Outgoing settings >> Trunk Name within your trunk configuration page, must be included within the parentheses on the settings above. For example, if you've specified callcentric (all lowercase) as presented above; please specify the above settings as-is. To further illustrate, if you've specified Trunk_1 for that option, you will need to include the following:
OLD Domain: callcentric.com NEW Domain: sip.callcentric.net
4) Verify Registration status under the Extensions page. If the Domain change caused your Registration to drop (it should not), please revert back to 'callcentric.com' and review Registration status. If you have any questions or need assistance, please open a Support Ticket