I need a SIP expert who is capable to install and configure the OPENSIPS SIP Registrar and Proxy server from [url removed, login to view] on my decicated Linux server (CentOS release 5.2) via remote ssh access. On that server, I have already installed and running Asterisk [url removed, login to view] and freePBX.
The aim is to be able to connect from a SIP client behind a NAT or directly on the Internet to that Opensips Server which has a public IP address.
As far as I understand, Asterisk alone is not a SIP Registrar and Proxy in every aspect. At least, I am not able to connect with my Zoiper SIP client behind a NAT to the Asterisk over the public Internet (and I do not want to setup a VPN tunnel to the Asterisk server).
This is not a commercial project but rather for education, so the budget is very limited.