Dedicated network environment with SMC2.0 + Standalone SC + VP9650 + TE endpoints. Branch TE40's SIP registration succeeds, but GK registration fails because no GK is found.
1. The TE endpoint initiates a dual-protocol registration with the standalone SC. The GK registration fails because no GK can be found. The SIP registration succeeds.
2. According to packet capture analysis on the TE endpoint and standalone SC, the endpoint sends the RRQ, but the standalone SC does not receive this registration request. Therefore, it is normal for the endpoint to report the error that the GK is not found. It is determined that there is network port limitation between the endpoint and the standalone SC.
3. Closely check the SIP registration of the branch endpoint. It is found that registration can succeed through TLS or TCP, but fails through UDD. Ask the user to check the firewall configuration again. It is found that the firewall policy allows only TCP packets from the branch endpoint's IP address to pass through. After the policy is modified to allow both TCP and UDP, the problem is solved.
The TE endpoint uses UDP (the User Datagram Protocol line highlighted in the red box in the following figure) for GK registration with the standalone SC. Therefore, when the firewall policy allows only TCP packets to pass through, the SIP registration succeeds and the GK registration fails.
The firewall allows only TCP packets to pass through.
Modify the firewall policy to allow both TCP and UDP packets to pass through.