Authorization on the provider's sip server through your server?

Question

SIP

Good day everyone!
I formulated the topic rather confusingly, but you will now understand why.
Task: Organize the authorization of sip clients on the server of the communication service provider, through its own server. Suppose the provider has a server auth.prov-server.ru and sip clients specify this server + login + password in the settings and work fine, so I need to specify auth.my-server.ru instead of auth.prov-server.ru ( my server), and it would forward all traffic to the provider's server auth.prov-server.ru
Why do I actually need all this.
In our company, many employees use personal mobile phones with special to use sip (mango, it can help in solving the problem). software.
Mango's servers are naturally available 24/7 and everything is fine, but I need employees to be able to connect to servers from home and call anywhere for their needs :)
Since mango has no restrictions on employees' working hours, I came up with the following scheme
: in the authorization server settings on my own, and directly on the server I forward ports to the mango server. Of course, I activate the forwarding rules at the right time for me.
It turns out that when the rules work, users connect and use the services, when there are no rules, nothing works.
To be honest, I am rather weak in the description of iptables rules and it is very difficult for me to implement such a scheme. If you help me, I will be infinitely grateful to you, since this is an interesting experience for me, and indeed a rather non-trivial task :) From the
available: Server ubuntu
server 12.04 I don’t understand which ports to forward and how to write routing rules from the Internet back to the Internet Thank you all very much!

Answer 1

The idea itself is a failure :) And if the client simply writes a mango server and works around it?) If you want to limit your funds, raise your freepbx, set up an outgoing trunk to the mango on it, and turn off everything else from the mango. Set limits inside your PBX and steer whoever you want.