Treat emergency calling as a deployment requirement
Emergency service behavior depends on the carrier, service type and jurisdiction. The FCC's US guidance explains that VoIP users may face location and power or internet limitations. That source is US-specific; obtain the applicable requirements for every location you operate.
Confirm location responsibilities
Ask the provider how a device or user location is registered and updated, including remote staff and shared desks. Document who owns those updates. An extension number or the address of the PBX server is not automatically the caller's current physical location.
Verify through an approved process
Arrange the provider's supported validation procedure. Do not place uncoordinated calls to an emergency center to test a new dialplan. Include dial permissions, destination handling and location presentation in the acceptance record.
Prepare for loss of service
Power protection must cover the phone, switches, router and access equipment required for calling. Internet failure can still remove service. Give staff a clear alternate calling procedure and explain relevant limitations to visitors or shared-space users. Revisit the plan after office moves, provider changes and remote-work policy changes. This page is an operational checklist, not a carrier guarantee or jurisdiction-specific legal determination.
Sources & applicability
Primary references for the technical details above. Operational examples and planning checklists are VoIP.info editorial guidance.