The 200 OK is fine. The address in c= is not.
The ladder completes. What do you open next?
10.1.2.3 is not a public address. The phone will send RTP there and get nothing back.
The trunk is up. The offer has no codec the answerer will take.
Where does 488 point?
488 is about this UA’s media, not about routing.
OPTIONS never completes. The certificate name and the Contact FQDN disagree.
The admin center says inactive. What must succeed first?
Direct Routing health is OPTIONS, and an IP in Contact is refused.
A diagnostic, not a recipe. The source address was never on the trust list.
The CDR export shows 200 calls to premium international destinations from one UDP source. First control to check?
IOS voice trusted-IP authentication is the documented toll-fraud control.
Both sides want a refresh. They never agreed the interval.
The second response is
422 and Min-SE are session timers.
The INVITE left without SDP. Something on the trunk demanded an MTP.
This INVITE is
No SDP in the INVITE means the offer is not here.
Two proxies keep sending the request to each other.
The response is 483 Too Many Hops. The header that ran out is
Each hop decrements Max-Forwards. Zero becomes 483.
The forwarded-from number never arrived.
The PBX sent Diversion. The SBC’s outbound INVITE has no Diversion and no History-Info. Unity keys the greeting from
Diversion is widely used and is not the standards-track history mechanism. History-Info is.