Locate the response family
- 1xx ProvisionalRequest is progressing
- 2xx SuccessRequest succeeded200 belongs here
- 3xx RedirectionAnother destination
- 4xx Request failureInterpret this request
- 5xx Server failureServer could not fulfil
- 6xx Global failureFailure across destinations
Read the status with its request method and call leg. For example, 200 after REGISTER confirms a binding; it does not prove an INVITE succeeded.
What this response means
The request succeeded under the responding system’s processing. Its practical meaning depends on the request method identified by CSeq.
Read it in context
A 200 to REGISTER accepts a registration transaction. A 200 to INVITE accepts the session request and requires the appropriate acknowledgement. A 200 to BYE confirms termination handling. These are different milestones.
Administrator checks
Match the response to its request and leg. For INVITE, inspect ACK and negotiated media. For REGISTER, inspect the returned bindings and expiry behavior. For BYE, confirm that the intended established session was ended.
Next action and common mistake
Do not use the presence of any 200 in a trace as proof that the business call succeeded. A registration can be healthy while routing fails, and an answered call can still have one-way sound.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.