Yes, what you are trying to do should work. In the first proxy field you need to put in the SIP service providers proxy address (this can be a FQDN or an IP address). If it is a FQDN you may need to check the two SRV options. The outbound proxy field may not need to be populated.
Have you looked at the SIP Trunks document on this community to see if someone has already posted a template for your SIP Provider?
I haven`t found any template related to my SIP Provider.
I`ve even contacted the IT manager of the telephone company (SIP Provider) and he suggested me to contact Cisco support community to figure out how to configure the router/PBX. He couldn`t provide me with any usefull information related to the (not) incoming call problem, except he mentioned that the UC320W doesn`t give any response when he sends an INVITE to it (to my IP address).
Any ideas if it`s even possible to fix my issue with this kind of SIP trunk configuration?
I realy have this feeling that I`m the first one who orders the SIP Trunk from this company.
Is the UC320W directly connected to the internet or do you have some other router/firewall between the UC320W and the Internet? If there is some other device in front of the UC320W, there may be some other configuration that may be needed such as port forwarding, or enabling SIP ALG, or NAT keep alive.
The UC320W has a security feature where we only allow SIP messages from IP addresses that we know about. It is best to use the proxy name instead of IP address and use DNS SRV if your provider support it. Often times the DNS SRV lookup will provide a primary and secondary IP address to use for SIP. When you use this method all of the IP addresses are added to the trusted SIP IP list.
You can also enable SIP troubleshooting logs from Status -> Support Tools -> Logs and see if you see the incoming SIP invite from the provider.
The UC320W is directly connected to the Internet. I`ve even contacted my ISP for detailed information about my internet connection and there aren`t any routers, switches or NAT that could block the incomming signal from SIP provider.
In Support Tools -> Logs I can see the INVITE only if I`m making an outgoing call, nothing for incomming.
I`m going to find out if my SIP Provider supports the proxy name feature (with DNS SRV), but I have doubts in that, so I must find a way to configure the UC320W with IP adresses only.
I think that it is time to make a call into the SBSC support center where an engineer can take a detailed look at your system's configuration. Please reference this thread on the community to give the engineer some background.
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