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Review SIP and media boundaries after voice-system changes

Review the boundary where phones, a PBX, a session border controller and the carrier meet. The aim is to catch undocumented changes before they complicate the next call failure.

Check what changed

  • Compare current SIP transport, listening ports and certificate expiry with the approved service record.
  • Confirm that documented RTP or SRTP ranges still match firewall rules and the provider agreement.
  • Review recent firmware, trunk and NAT changes for altered signalling or media routes.

Test a representative path

Place a controlled inbound and outbound test call through the boundary. Record whether setup, two-way audio and teardown work. Rotate the endpoint or carrier route tested each month; one successful call does not certify every route.

Assign an owner to each mismatch and retain the configuration version used in the test. The VoIP protocols reference explains the different functions of signalling and media.